From Chapter Four of my book, A Biblical Critique of Calvinism (Oct. 2012)
To procure the favour of God, human merits are ever and anon obtruded, and very frequently while Christ is passed by, God is supplicated in their name. I ask if this is not to transfer to them that office of sole intercession which we have above claimed for Christ? Then what angel or devil ever announced one syllable to any human being concerning that fancied intercession of theirs? There is not a word on the subject in Scripture. What ground then was there for the fiction? Certainly, while the human mind thus seeks help for itself in which it is not sanctioned by the word of God, it plainly manifests its distrust (see s. 27). But if we appeal to the consciences of all who take pleasure in the intercession of saints, we shall find that their only reason for it is, that they are filled with anxiety, as if they supposed that Christ were insufficient or too rigorous. By this anxiety they dishonour Christ, and rob him of his title of sole Mediator, a title which being given him by the Father as his special privilege, ought not to be transferred to any other. By so doing they obscure the glory of his nativity and make void his cross; in short, divest and defraud of due praise everything which he did or suffered, since all which he did and suffered goes to show that he is and ought to be deemed sole Mediator. (Institutes of the Christian Religion, III, 20:21)
And though believers mutually offer up prayers to God in behalf of their brethren, we have shown that this derogates in no respect from the sole intercession of Christ, because all trust to that intercession in commending themselves as well as others to God. Moreover, we have shown that this is ignorantly transferred to the dead, of whom we nowhere read that they were commanded to pray for us. The Scripture often exhorts us to offer up mutual prayers; but says not one syllable concerning the dead; nay, James tacitly excludes the dead when he combines the two things, to “confess our sins one to another, and to pray one for another,” (James 5:16). Hence it is sufficient to condemn this error, that the beginning of right prayer springs from faith, and that faith comes by the hearing of the word of God, in which there is no mention of fictitious intercession, superstition having rashly adopted intercessors who have not been divinely appointed. While the Scripture abounds in various forms of prayer, we find no example of this intercession, without which Papists think there is no prayer. Moreover, it is evident that this superstition is the result of distrust, because they are either not contented with Christ as an intercessor, or have altogether robbed him of this honour. (III, 20:27)
There is more than a little in Holy Scripture (despite Calvin’s denials) about the intercession of angels and saints:
Matthew 17:3 (RSV, as throughout) And behold, there appeared to them Moses and Eli’jah, talking with him. (cf. Mk 9:4; Lk 9:30-31)
These departed saints show a deep interest in human affairs: enough to even appear on earth again. It is quite plausible, then, to postulate that they also intercede for us.
Jeremiah 15:1 Then the LORD said to me, “Though Moses and Samuel stood before me, yet my heart would not turn toward this people. . . .”
The assertion of the hypothetical scenario shows that it is possible (and likely that it actually occurs). Moses and Samuel were renowned for their intercessory powers (Ex 32:11-12; 1 Sam 7:9; Ps 99:6). Calvin replies to this as follows:
How (they ask) could he have spoken thus of the dead but because he knew that they interceded for the living? My inference, on the contrary, is this: since it thus appears that neither Moses nor Samuel interceded for the people of Israel, there was then no intercession for the dead. For who of the saints can be supposed to labour for the salvation of the peoples while Moses who, when in life, far surpassed all others in this matter, does nothing? Therefore, if they persist in the paltry quibble, that the dead intercede for the living, because the Lord said, “If they stood before me,” (intercesserint), I will argue far more speciously in this way: Moses, of whom it is said, “if he interceded,” did not intercede for the people in their extreme necessity: it is probable, therefore, that no other saint intercedes, all being far behind Moses in humanity, goodness, and paternal solicitude. Thus all they gain by their caviling is to be wounded by the very arms with which they deem themselves admirably protected. But it is very ridiculous to wrest this simple sentence in this manner; for the Lord only declares that he would not spare the iniquities of the people, though some Moses or Samuel, to whose prayers he had shown himself so indulgent, should intercede for them. (III, 20:23)
Calvin is fundamentally confused in this analysis of his. The text doesn’t say that Moses and Samuel absolutely would not pray for their people. It is about God’s decision, whether or not they intercede. It appears that they had not interceded in this instance, but Calvin’s absurd and unfounded conclusions (“there was then no intercession for the dead’; “it is probable, therefore, that no other saint intercedes”) don’t follow.
His conclusion is premature because we don’t have full information why Moses and Samuel didn’t intercede. There are valid reasons other than a stipulation that they never did so or that no dead saint ever does or could. Perhaps, for example, they already knew that God’s answer would be “no.”
If we have a reasonable assurance that God will not grant a particular prayer, then we don’t pray it. This is all the more applicable to perfected saints in heaven. Elsewhere (see the appendix) Calvin grants that dead saints can and do pray, so he’s not even fully consistent with himself.
Jeremiah himself is described as praying for the Jews and Jerusalem, in the Deuterocanon:
2 Maccabees 15:13-14 Then likewise a man appeared, distinguished by his gray hair and dignity, and of marvelous majesty and authority.  And Onias spoke, saying, “This is a man who loves the brethren and prays much for the people and the holy city, Jeremiah, the prophet of God.”
The following two descriptions show us that creatures (whether men or angels) are functioning as intercessors and mini-intermediaries of sorts, between men and God. Otherwise, what are they doing with “the prayers of the saints”? If those went right to God only, why would this be mentioned at all?
Revelation 5:8 And when he had taken the scroll, the four living creatures and the twenty-four elders fell down before the Lamb, each holding a harp, and with golden bowls full of incense, which are the prayers of the saints;
Revelation 8:3-4 And another angel came and stood at the altar with a golden censer; and he was given much incense to mingle with the prayers of all the saints upon the golden altar before the throne;  and the smoke of the incense rose with the prayers of the saints from the hand of the angel before God.
Calvin makes an illegitimate reply to this biblical argument:
In endeavouring to prove that such intercession derives some support from Scripture they labour in vain. We frequently read (they say) of the prayers of angels, and not only so, but the prayers of believers are said to be carried into the presence of God by their hands. But if they would compare saints who have departed this life with angels, it will be necessary to prove that saints are ministering spirits, to whom has been delegated the office of superintending our salvation, to whom has been assigned the province of guiding us in all our ways, of encompassing, admonishing, and comforting us, of keeping watch over us. All these are assigned to angels, but none of them to saints. How preposterously they confound departed saints with angels is sufficiently apparent from the many different offices by which Scripture distinguishes the one from the other. No one unless admitted will presume to perform the office of pleader before an earthly judge; whence then have worms such license as to obtrude themselves on God as intercessors, while no such office has been assigned them? God has been pleased to give angels the charge of our safety. (III, 20:23)
Calvin neglects to see that the 24 “elders” (regarded by most commentators as dead human beings) serve the same function as the angels, regarding “the prayers of the saints.” They both possess them, and they both present them to God. Our present concern is intercession of saints and angels, not every attribute that an angel has, over against a departed saint.Calvin makes a failed attempt at obfuscation of the issue by introducing irrelevant, extraneous elements: an old lawyer’s trick. Such tactics may read or sound impressive, but the problem is that it is an illogical, fallacious argument. Rhetorically, it may work (the endeavor to persuade), but logically and biblically it fails.
These passages in Revelation 5 and 8 also seem to make reference to, or at least express the same notion seen in another deuterocanonical passage:
Tobit 12:12-15 “And so, when you and your daughter-in-law Sarah prayed, I brought a reminder of your prayer before the Holy One; and when you buried the dead, I was likewise present with you.  When you did not hesitate to rise and leave your dinner in order to go and lay out the dead, your good deed was not hidden from me, but I was with you.  So now God sent me to heal you and your daughter-in-law Sarah.  I am Raphael, one of the seven holy angels who present the prayers of the saints and enter into the presence of the glory of the Holy One.”
Again, we see another biblical example (in a book Calvin fully accepts as canonical) of dead saints praying an “imprecatory prayer”:
Revelation 6:9-10 When he opened the fifth seal, I saw under the altar the souls of those who had been slain for the word of God and for the witness they had borne;  they cried out with a loud voice, “O Sovereign Lord, holy and true, how long before thou wilt judge and avenge our blood on those who dwell upon the earth?”
These sorts of prayers recognize God’s role as a just judge Who will vindicate His people. Similar examples can be found in the Psalms (35, 59, 69, 79, 109, 139) and Jeremiah (chapters 11, 15, 18, 20); also in Zechariah 1:12 (from an angel).
We know that men talk to angels often in Scripture; therefore they are communicating to creatures from the realm of heaven (thus, by analogy, could ask them to pray as well, since they are clearly aware of earthly affairs). We also know that men make (successful) requests or petitions of angels (Gen 19:15, 18-21; 32:24-29; 48:14-16). Angels even participate in distributing grace (Rev 1:4).
. . . they do not, however, lose their quiescence so as to be distracted with earthly cares: far less are they, therefore, to be invoked by us. Nor does it follow that such invocation is to be used because, while men are alive upon the earth, they can mutually commend themselves to each other’s prayers. It serves to keep alive a feeling of charity when they, as it were, share each other’s wants, and bear each other’s burdens. This they do by the command of the Lord, and not without a promise, the two things of primary importance in prayer. But all such reasons are inapplicable to the dead, with whom the Lord, in withdrawing them from our society, has left us no means of intercourse (Eccles. 9:5, 6), and to whom, so far as we can conjecture, he has left no means of intercourse with us. But if any one allege that they certainly must retain the same charity for us, as they are united with us in one faith, who has revealed to us that they have ears capable of listening to the sounds of our voice, or eyes clear enough to discern our necessities? Our opponents, indeed, talk in the shade of their schools of some kind of light which beams upon departed saints from the divine countenance, and in which, as in a mirror, they, from their lofty abode, behold the affairs of men; but to affirm this with the confidence which these men presume to use, is just to desire, by means of the extravagant dreams of our own brain, and without any authority, to pry and penetrate into the hidden judgments of God, and trample upon Scripture, which so often declares that the wisdom of our flesh is at enmity with the wisdom of God, utterly condemns the vanity of our mind, and humbling our reason, bids us look only to the will of God. (III, 20:24)
It’s simply not true that there are “no means of intercourse” any longer with the dead. God obviously thought it was meaningful for dead people to appear again on the earth, on several recorded occasions: 1) Samuel (1 Sam 28:12-15; cf. Sirach 46:20), 2) Elijah and Moses (Mt 17:1-3), 3) The ones who rose from their graves after Jesus’ resurrection (Mt 27:50-53), 4) The two witnesses of Revelation (11:3).
Invocation of saints and angels follows quite logically and straightforwardly from what we know (as presented in Holy Scripture):
1) We ask others on earth to pray for us (Rom 15:30; Eph 6:19; Col 4:3-4; 1 Thess 5:25; 2 Thess 3:1; Heb 13:18).
2) Members of the Body of Christ pray to God for each other (Mt 5:44; Acts 8:15; 9:40; 28:8; 2 Cor 9:14; 13:9; Eph 6:18; Phil 1:9, 19; Col 1:3, 9; 2 Thes 1:11; 1 Tim 2:1; Phm 1:22; Jas 5:14,1 6; 3 Jn 1:2).
3) Saints in heaven, filled with grace and united to Christ, are still members of the Body of Christ (Rom 12:4-5; 1 Cor 12:13, 26; 2 Cor 2:5; Eph 1:9-10; 2:19-21; 4:15-16, 25; Col 2:18-19; Heb 13:3).
4) Angels (many passages) and dead saints (Rev 6:9-10) care very much for us, and are just as alive as we are; in fact, far more intensely alive (Mt 22:32; Lk 20:37-38; Rom 8:13, 35-39; 1 Cor 15:54-55).
5) Angels are aware of earthly events (Lk 15:10, 1 Cor 4:9, and many other passages); so are dead saints (Heb 12:1). Moreover, angels are extremely intelligent and can deduce our thoughts and follow our actions.
6) The Bible says that the prayers of the righteous are very powerful in their effects (Jas 5:16-18). How much more the prayers of perfected saints (Mt 22:30; 1 Jn 3:2) and always-sinless angels?
7) We observe both angels (Rev 8:3-4; cf. Tob 12:12-15) and dead saints (Rev 5:8) presenting our prayers to God, and know from other passages that they intercede for us (Jer 15:1; 2 Macc 15:13-14; Rev 6:9-10).
8) Men also talk to dead men (1 Sam 28:12-15; cf. Sir 46:20; Mt 17:1-3; 27:50-53; Rev 11:3) and angels on numerous occasions, and angels initiate discourse with human beings (Gen 21:17-18; when Jesus Christ was born); this is scarcely distinguishable from invocation of them.
9) Petitions made to angels are granted (Gen 19, 32, 48).
10) Therefore, it follows that we can ask either to intercede.
See many more articles on these topics on my Saints, Purgatory, & Penance web page.