This is taken from Chapter 12 of my book, Biblical Catholic Salvation (2010), pages 115-129.
Charles Hodge describes the Calvinist notion of irresistible grace (in his mind, “Augustinian” is essentially synonymous with “Calvinist” or “Reformed”):
This general call of the gospel is not inconsistent with the doctrine of predestination. For predestination concerns only the purpose of God to render effectual in particular cases, a call addressed to all. A general amnesty on certain conditions may be offered by a sovereign to rebellious subjects, although he knows that through pride or malice many will refuse to accept it; and even although, for wise reasons, he should determine not to constrain their assent, supposing that such influence over their minds were within his power. It is evident from the nature of the call that it has nothing to do with the secret purpose of God to grant his effectual grace to some and not to others. All the call contains is true. The plan of salvation is designed for men. It is adapted to the condition of all. It makes abundant provision for the salvation of all. The promise of acceptance on the condition of faith is made to all. And the motives and reasons which should constrain obedience are brought to bear on every mind to which the call is sent. According to the Augustinian scheme, the non-elect have all the advantages and opportunities of securing their salvation, that, according to any other scheme, are granted to mankind indiscriminately. Augustinianism teaches that a plan of salvation adapted to all men and adequate for the salvation of all, is freely offered to the acceptance of all, although in the secret purpose of God, he intended that it should have precisely the effect which in experience it is found to have. He designed in its adoption to save his own people, but consistently offers its benefits to all who are willing to receive them. (§2. The External Call) . . .
Why does one man repent and believe the Gospel, while another remains impenitent? The Augustinian says it is because God makes them to differ. He gives to one what He does not give to another. All Anti-Augustinians say that the reason is, that the one cooperates with the grace of God, and the other does not; or, the one yields, and the other does not; or, that the one resists, and the other does not. . . . God knows just what kind and degree of influence will be effectual in determining the will of a given person, under given circumstances, and in a given state of mind. And this influence he determines to exert with the purpose of securing the sinner’s conversion, and with the certain foreknowledge of success. . . .
According to the Augustinian doctrine the efficacy of divine grace in regeneration depends neither upon its congruity nor upon the active cooperation, nor upon the passive non-resistance of its subject, but upon its nature and the purpose of God. It is the exercise of “the mighty power of God,” who speaks and it is done. . . .
It will of course be admitted that, if efficacious grace is the exercise of almighty power it is irresistible. That common grace, or that influence of the Spirit which is granted more or less to all men is often effectually resisted, is of course admitted. That the true believer often grieves and quenches the Holy Spirit, is also no doubt true. And in short that all those influences which are in their nature moral, exerted through the truth, are capable of being opposed, is also beyond dispute. But if the special work of regeneration, in the narrow sense of that word, be the effect of almighty power, then it cannot be resisted, any more than the act of creation. The effect follows immediately on the will of God, as when He said let there be light, and light was. (§4. Efficacious Grace) (Systematic Theology, three-volume edition [Charles Scribner and Company: 1871; reprinted by William B. Eerdmans Publishing Co. [Grand Rapids, Michigan, 1940]; Volume II, Part III, Chapter 4: “Vocation”)
Ludwig Ott elucidates the opposing Catholic position:
Since God gives sufficient grace to all men, in order that they may work out their salvation, and since, in fact, only a part of mankind achieves salvation, there are graces which have as a consequence the salutary effect intended by God, i.e., efficacious graces (gratiae efficaces), and graces, which do not have this effect, i.e., merely sufficient graces (gratiae mere sufficientes). There is a question as to whether the ground for this difference in efficacy lies in the grace itself or in human freedom. The Reformers and the Jansenists sought to solve this difficult question radically by denying the freedom of the will. Cf. Luther, De Servo arbitrio [The Bondage of the Will] . . .
Innocent X condemned as heretical the following proposition of Cornelius Jansen: “In the condition of fallen nature interior grace is never resisted.” D [Denzinger] 1093, cf. D 797, 815 et seq., 1094 et seq.
Holy Scripture stresses both the human factor of the freedom of the will, and the Divine factor of grace . . .
St. Augustine, to whom the opponents of this doctrine appeal, never denied the freedom of the will in relation to grace. In defence of the freedom of the will he wrote, in the year 426 or 427, the work, De gratia et libero arbitrio, in which he seeks to intrust and to appease those, “who believe that free will is denied, if grace defended, and who so defend free will, that they deny grace and maintain that grace is given according to our merits” (1, 1). Justification is not only a work of grace, but at the same time a work of the free will: “He who created thee without thy help does not justify thee without thy help” (Sermo 169, 11, 13) . . .
St. Augustine also knows substantially the difference between merely sufficient grace and efficacious grace. Cf. De spiritu et litt. 34, 60: “His mercy comes before us in everything. But to assent to or dissent from the call of God is a matter for one’s own will.” (Fundamentals of Catholic Dogma [Rockford, Illinois: TAN Books, 1974; originally 1952], translated by Patrick Lynch, 246-247; italics for Latin and book titles added)
The Council of Trent declared, along these lines, in its canons and decrees on justification:
Canon 4 If anyone shall say that man’s free will moved and aroused by God does not cooperate by assenting to God who rouses and calls, whereby it disposes and prepares itself to obtain the grace of justification, and that it cannot dissent, if it wishes, but that like something inanimate it does nothing at all and is merely in a passive state: let him be anathema.
Canon 5 If anyone shall say that after the sin of Adam man’s free will was lost and destroyed, or that it is a thing in name only, indeed a title without a reality, a fiction, moreover, brought into the Church by Satan: let him be anathema.
Canon 6 If anyone shall say that it is not in the power of man to make his ways evil, but that God produces the evil as well as the good works, not only by permission, but also properly and of Himself, so that the betrayal of Judas is no less His own proper work than the vocation of Paul: let him be anathema.
Decrees, Chapter 5 (On the Necessity of Preparation for Justification of Adults, and Whence it Proceeds)
It [the Synod] furthermore declares that in adults the beginning of that justification must be derived from the predisposing grace [can. 3] of God through Jesus Christ, that is, from his vocation, whereby without any existing merits on their part they are called, so that they who by sin were turned away from God, through His stimulating and assisting grace are disposed to convert themselves to their own justification, by freely assenting to and cooperating with the same grace [can. 4 and 5], in such wise that, while God touches the heart of man through the illumination of the Holy Spirit, man himself receiving that inspiration does not do nothing at all inasmuch as he can indeed reject it, nor on the other hand can he [can. 3] of his own free will without the grace of God move himself to justice before Him. Hence, when it is said in the Sacred Writings: “Turn ye to me, and I will turn to you” [Zach. 1:3], we are reminded of our liberty; when we reply: “Convert us, O Lord, to thee, and we shall be converted” [Lam. 5:21], we confess that we are anticipated by the grace of God.
We should also be familiar with some of the shocking views of Martin Luther regarding free will, in his 1525 book, The Bondage of the Will (his own favorite, and, as many believe, his most influential and/or important book):
So man’s will is like a beast standing between two riders. If God rides, it wills and goes where God wills: as the Psalm says, ‘I am become as a beast before thee, and I am ever with thee’ (Ps. 72.22-3). If Satan rides, it wills and goes where Satan wills. Nor may it choose to which rider it will run, or which it will seek; but the riders themselves fight to decide who shall have hold of it. (The Bondage of the Will, translated by J. I. Packer and O. R. Johnston [Grand Rapids, Michigan: Fleming H. Revell, 1957], 103-104)
It is, then, fundamentally necessary and wholesome for Christians to know that God foreknows nothing contingently, but that He foresees, purposes, and does all things according to His own immutable, eternal and infallible will. This bombshell knocks ‘free-will’ flat, and utterly shatters it; so that those who want to assert it must either deny my bombshell, or pretend not to notice it, or find some other way of dodging it. (Ibid., 80)
From which it follows, by resistless logic, that all we do, however it may appear to us to be done mutably and contingently, is in reality done necessarily and immutably in respect of God’s will. (Ibid., 80)
Now, if you are disturbed by the thought that it is difficult to defend the mercy and justice of God when he damns the undeserving, that is to say, ungodly men who are what they are because they were born in ungodliness and can in no way help being and remaining ungodly and damnable, but are compelled by a necessity of nature to sin and to perish (as Paul says: “We were all children of wrath like the rest,” since they are created so by God himself from seed corrupted by the sin of the one man Adam)—rather must God be honored and revered as supremely merciful toward those whom he justifies and saves, supremely unworthy as they are, and there must be at least some acknowledgment of his divine wisdom so that he may be believed to be righteous where he seems to us to be unjust. For if his righteousness were such that it could be judged to be righteous by human standards, it would clearly not be divine and would in no way differ from human righteousness. But since he is the one true God, and is wholly incomprehensible and inaccessible to human reason, it is proper and indeed necessary that his righteousness also should be incomprehensible, . . . (Phillip S. Watson, editor and translator, The Bondage of the Will, in Luther’s Works, Vol. 33: Career of the Reformer III [Augsburg / Fortress Press, 1957], 289)
God’s love toward men is eternal and immutable, and his hatred is eternal, being prior to the creation of the world, and not only to the merit and work of free choice; and everything takes place by necessity in us, according as he either loves or does not love us from all eternity, . . . (Ibid., 198)
The main issue having to do with “irresistible grace” revolves around whether those who aren’t saved have resisted salvation with their free will, or if God predestined them to hell. Catholics deny the latter (a corollary of limited atonement).
God’s grace is freely rejected by those who don’t want either God or His grace. Calvinists deny this by asserting that those who are saved are saved because of a grace that they can’t resist, whereas those who are unfortunate enough to not be among those whom God has chosen to save, cannot possibly freely choose to reject God, since they could not have done otherwise, in any event.
If some are irresistibly chosen, apart from their will, then others are, by logical necessity, irresistibly lost, also apart from their will. But this is not what the Bible teaches (not a small problem). We deny (based on much biblical data) that it is impossible for either the damned or the saved to do otherwise.
Perhaps an analogy would be helpful at this point. Children have free will, and can decide to spurn even a very good Christian upbringing. So it is also with God and His children (even the extent of hell existing, since it is the place where a man can remove himself from God forever). God can love us and at the same time allow us to reject Him without ceasing to love us.
Just because He judges sinners and the reprobate doesn’t require a cessation of love. That simply doesn’t follow. When an earthly judge sentences a man to hanging, he doesn’t necessarily have to hate the man. Chances are he pities him, which is as much an aspect of love as anything else. Why should we think that God has less mercy and pity on Him than even a virtuous pagan does? Insofar as Calvinism holds to such a view (perhaps it doesn’t, or else Calvinists differ amongst themselves), we find it quite objectionable and incomprehensible.
God gave men the free will to either accept Him and be saved entirely by His grace or to reject Him and suffer the eternal consequences. Hell was created for the devil and his fallen angels, but it seems that many human beings would rather go there than follow God’s commands and accept His free offer of grace and salvation and be with Him forever.
The damned have made their fatal choice. God simply calls a spade a spade and makes it irrevocable by His judgment. Their time to repent has run out, and so God judges them. And His judgment is just. But justice is not antithetical to love. They are not opposite characteristics. They are complementaries.
Hell is not a function of love, but of justice. But in a sense God loves men so much that He honors their free will even to the extent that they may choose to deny Him. God allowed men to utterly reject Him in His passion and crucifixion: all the while asking the Father to forgive them in their ignorance. He kept loving them. It makes no sense to believe that God stops loving men who choose to reject Him and therefore end up in hell.
God doesn’t predestine anyone to hell from all eternity, without any consideration of their free will actions whatever, as Calvinists teach (as irresistible grace and limited atonement require). The damned are deceived, but they don’t want God, and hell is the utter absence of God and all that flows from Him. No doubt they will regret their choice of going there, shortly after they arrive.
Do we say of the convicted criminal, “he is in jail because of the jury [or the judge]”? We could say that in one limited sense (it is true in terms of verdict and sentencing), but we are much more likely to say that he is there because of the crime he committed. We place the blame and the cause back on him, not on the ones who were executing justice and protecting society.
Likewise, by analogy, we can say that people choose to go to hell, and they are there through their own fault and choice (not God’s sole choice from all eternity). There is nothing inconsistent with saying that while at the same time asserting that there was such a thing as sentencing and legal justice, too.
God is just but also loving and does not cease to be so in exercising His just wrath and punishment and judgment, just as Jesus did not cease to be loving when He cleared the temple or excoriated the Pharisees for their hypocrisy. We reject the premise and false dichotomy of maintaining that somehow the justice of God contradicts His lovingkindness (leading to the unbiblical position that God didn’t or doesn’t love the people who wound up in hell).
The Catholic position (and indeed any non-Calvinist Christian position on these matters) does not require moving God out of the equation. God passes sentence and judges. But He judges the reprobate based on how a person has behaved and whether the person accepted His free gift of salvation or not. That is the criterion.
The Bible in accounts of judgment scenarios (especially in Matthew 25:31-46) thus overwhelmingly emphasizes the works that a person did or didn’t do. This in turn strongly suggests that the person’s free will decisions led him or her to hell, in that terrible event that they are damned, not God’s choice from eternity, so that they were essentially created from the beginning to wind up in hell
A large part of the horrific experience of hell will be the thought and unfathomable sense of regret of the reprobate: “I never had to end up here at all, but I chose to reject every overture that God and Christians made, to urge and help me to change my evil ways.”
But will they think God “sent” them there by His eternal decree alone (as Calvinists assert)? They might (since a distorted self-image and notion of God ties into all this), but they will know for eternity that God did indeed offer them a free gift of salvation, and they refused to accept it. But in Calvinism, all of that is nonsensical and precluded from the outset, because there is no free will to accept salvation or spurn God’s grace (which is supposedly “irresistible”).
God makes those choices (and only He can do so, for the Calvinist). Therefore, people in hell are there because God chose to not extend the grace to them that they would have been unable to resist, had God decided to send it their way. All men were equally fallen and corrupt, but we are led to believe that God simply chose some and rejected others. The choices of men had nothing whatever to do with it, since their free will was utterly destroyed by the fall.
Such a doctrine, we believe (based on the revelation of Holy Scripture, and how God has revealed Himself in history and in the Person of Jesus), corrupts both the love and mercy, and justice of God.
Sinners certainly do have the power to resist God’s grace (which means hell in the end). Scripture repeatedly affirms this:
Proverbs 1:23-25 Give heed to my reproof; behold, I will pour out my thoughts to you; I will make my words known to you.  Because I have called and you refused to listen, have stretched out my hand and no one has heeded,  and you have ignored all my counsel and would have none of my reproof,
Luke 7:30 but the Pharisees and the lawyers rejected the purpose of God for themselves, not having been baptized by him
Luke 18:22-25 And when Jesus heard it, he said to him, “One thing you still lack. Sell all that you have and distribute to the poor, and you will have treasure in heaven; and come, follow me.”  But when he heard this he became sad, for he was very rich.  Jesus looking at him said, “How hard it is for those who have riches to enter the kingdom of God!  For it is easier for a camel to go through the eye of a needle than for a rich man to enter the kingdom of God.”
This passage shows that some things a person believes or wills can make it more difficult for them to follow Jesus and become a Christian. They are resisting God’s grace. If Calvinism were true, it seems that Jesus would have to say that riches would be irrelevant to whether someone was saved or not, or even regarding how difficult it would be for them to be saved. Grace would be irresistible. No one who was called by God would be resisting the push towards grace and God at all.
John 5:39-40 You search the scriptures, because you think that in them you have eternal life; and it is they that bear witness to me;  yet you refuse to come to me that you may have life.
Acts 7:51 You stiff-necked people, uncircumcised in heart and ears, you always resist the Holy Spirit. As your fathers did, so do you. (cf. Hosea 4:6-7)
How can anyone resist the Holy Spirit, if He is calling them (for that is also grace)?
Acts 26:14-15 And when we had all fallen to the ground, I heard a voice saying to me in the Hebrew language, ‘Saul, Saul, why do you persecute me? It hurts you to kick against the goads.’  And I said, ‘Who are you, Lord?’ And the Lord said, ‘I am Jesus whom you are persecuting.’
God Himself says that Paul was formerly resisting His grace, but then he stopped doing so and was converted.
Romans 1:18-25 For the wrath of God is revealed from heaven against all ungodliness and wickedness of men who by their wickedness suppress the truth.  For what can be known about God is plain to them, because God has shown it to them.  Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse;  for although they knew God they did not honor him as God or give thanks to him, but they became futile in their thinking and their senseless minds were darkened.  Claiming to be wise, they became fools,  and exchanged the glory of the immortal God for images resembling mortal man or birds or animals or reptiles.  Therefore God gave them up in the lusts of their hearts to impurity, to the dishonoring of their bodies among themselves,  because they exchanged the truth about God for a lie and worshiped and served the creature rather than the Creator, who is blessed for ever! Amen.
It is not a matter of these men being completely blind from all eternity: having been predestined to never receive the truth or salvation; therefore not able to resist what was never presented. To the contrary, God has given them much grace and knowledge of the truth, and they are resisting it; indeed the “suppress” what they truly know; what is “plain.” Therefore, they are damned because of what they know; not because of what they don’t know or never could have known.
They were not totally depraved from the beginning, but rather, they became progressively worse, becoming “futile in their thinking,” with their minds increasingly darkened. It was only after they resisted grace and truth that this happened. Calvinists have it exactly backwards, if we are to believe this passage.
Romans 2:4-5 Or do you presume upon the riches of his kindness and forbearance and patience? Do you not know that God’s kindness is meant to lead you to repentance?  But by your hard and impenitent heart you are storing up wrath for yourself on the day of wrath when God’s righteous judgment will be revealed.
2 Corinthians 4:3-4 And even if our gospel is veiled, it is veiled only to those who are perishing.  In their case the god of this world has blinded the minds of the unbelievers, to keep them from seeing the light of the gospel of the glory of Christ, who is the likeness of God.
This is a fascinating passage, in what it reveals about our present subject. In referring to those who are “perishing” and the “unbelievers,” St. Paul doesn’t say that their minds are utterly blind, as if there were no chance at all for them to receive grace and salvation (being among those who are damned and excluded from grace and the atonement and election, as Calvinism would have it).
Rather, he says that Satan has blinded them “from seeing the light of the gospel” – which is “veiled” as a result. The implication is that if they weren’t blinded by Satan (as opposed to by God for all eternity in relation to grace and salvation), they would indeed possibly be able to be saved. It makes no sense for Satan to try to cover the eyes of those who are constitutionally blind (by God’s decree). It must, then, be possible for them to (spiritually) see. Otherwise, the text makes no sense.
Therefore, the alleged ironclad, watertight Calvinist categories of those who are the recipients of grace (who can’t resist it) and those who are not (who can’t possibly receive it) are ruled out by simple deductive logic. A similar scenario and dynamic occurs in the parable of the sower:
Luke 8:11-12 Now the parable is this: The seed is the word of God.  The ones along the path are those who have heard; then the devil comes and takes away the word from their hearts, that they may not believe and be saved. (cf. Mt 13:19; Mk 4:15)
The “ones along the path” are regarded by most Bible commentators as representative of unbelievers. What is most notable here is, again, how Satan reacts. In cross-reference Mark 4:15 it says he “immediately comes” to take away the seed. Under Calvinist presuppositions, the person involved is damned from all eternity, and it is irrelevant as to salvation, whether he hears the Word or the gospel or not.
So why is the devil so concerned that he not hear it? This is a person already destined for hell; in the devil’s thorny grasp. Yet Luke even tells us why Satan does it: to take out a possibility that they would “believe and be saved.” Thus, Satan seems to believe that men will believe if they hear the gospel.
He is unaware (if Calvinism is true) that these things are already decided by God’s eternal decree, so that there is no pressing need to prevent knowledge of the Bible — all person’s eternal destinies already being sealed. But it makes perfect sense under the assumptions of Romans 10:17: “So faith comes from what is heard, and what is heard comes by the preaching of Christ.”
Galatians 1:6 I am astonished that you are so quickly deserting him who called you in the grace of Christ and turning to a different gospel –
Galatians 5:4 You are severed from Christ, you who would be justified by the law; you have fallen away from grace.
1 Timothy 1:19 holding faith and a good conscience. By rejecting conscience, certain persons have made shipwreck of their faith,
Hebrews 4:2 For good news came to us just as to them; but the message which they heard did not benefit them, because it did not meet with faith in the hearers.
Hebrews 10:29 How much worse punishment do you think will be deserved by the man who has spurned the Son of God, and profaned the blood of the covenant by which he was sanctified, and outraged the Spirit of grace?
Hebrews 12:15 See to it that no one fail to obtain the grace of God; that no “root of bitterness” spring up and cause trouble, and by it the many become defiled;
Jude 1:4 For admission has been secretly gained by some who long ago were designated for this condemnation, ungodly persons who pervert the grace of our God into licentiousness and deny our only Master and Lord, Jesus Christ.
How can they “pervert” something they supposedly never had in the first place or a thing that was “irresistible”?
Divine grace and human free will are also presented as perfectly compatible with each other:
Romans 8:28 We know that in everything God works for good with those who love him, who are called according to his purpose.
1 Corinthians 3:6-10 I planted, Apol’los watered, but God gave the growth.  So neither he who plants nor he who waters is anything, but only God who gives the growth.  He who plants and he who waters are equal, and each shall receive his wages according to his labor.  For we are God’s fellow workers; you are God’s field, God’s building.  According to the grace of God given to me, like a skilled master builder I laid a foundation, and another man is building upon it. Let each man take care how he builds upon it. (cf. Mk 16:20; Acts 13:2-4)
1 Corinthians 15:10 But by the grace of God I am what I am, and his grace toward me was not in vain. On the contrary, I worked harder than any of them, though it was not I, but the grace of God which is with me. (cf. 15:58)
2 Corinthians 6:1 Working together with him, then, we entreat you not to accept the grace of God in vain.
Philippians 2:12-13 . . . work out your own salvation with fear and trembling;  for God is at work in you, both to will and to work for his good pleasure. (cf. Acts 17:28; 1 Cor 12:6; Eph 2:10; 2 Pet 1:3-4, 10)
Summary: Do human beings have the free will to either accept or reject God’s grace, or is the Calvinist doctrine of irresistible grace biblical and true? I contend for the former, from Scripture.