All writings, both of secular and divine wisdom, yield instruction when effort is applied. – Olympiodorus, Commentary on Ecclesiastes.
There are many rabble rousers on the net seeking to attack bishops who have given support to priests that study and engage non-Christian religious traditions, seeking to find the good within them and using them to edify the Christian faithful. So many are quick to condemn bishops; they think of themselves as judges, rashly denouncing what they do not know. Recently, one can find some claiming Catholics are being turned against the Christian faith, becoming idolaters who break the First Commandment, because Catholics are being encouraged to study Indian spiritual traditions. Sadly, they act like as if they are bishops, claiming authority to proclaim anathemas which are not their own, making them pseudo-bishops. It is these pseudo-bishops with cult-like followings who are doing the Christian faith a disservice and are turning Catholics away from its own tradition, a tradition which recognizes many things of value, many rays of truth, in non-Christian faiths. Throughout the centuries, Christians have sought wisdom in non-Christian sources and, after much diligent study, found the treasure which they sought.
Though it might take effort and adaptation, Christians have been able to show the benefit of non-Christian literature and its place in Christian education. St. Clement of Alexandria saw pagan philosophy as being capable of directing the mind so as to serve as an introductory catechesis, preparing the mind for the transcendent truths of Christian revelation. Just because the source was non-Christian did not mean there was not some sense of divine providence involved in its creation. A Christian should be a lover of wisdom, and so should love the seeds of wisdom sown throughout the world. They should seek to nurture them and sprout instead of rooting them out of them ground, destroying what God had planted for the good of creation.
Even though “fools despise wisdom and instruction” (Prov. 1:7b RSV), these Christians preach that such a search through pagan wisdom is idolatrous and an unworthy pursuit. One can but wonder if they realize how much of the pagan tradition survives in the modern world, how much of the advances of pagan learning they employ for their daily lives? Clearly, just because something is discovered by a pagan does not mean it is something we should ignore, but yet, if that is the case, how can we ignore the wisdom of the pagans, how can we not treat it as something worthy of our investigation?
Great men and women of the Christian faith have recorded, time and time again, reasons why they do not limit themselves to Christian literature, and yet, in every generation, we find some new interest in some pagan tradition causing outcries among Christians as if the faith was about to be destroyed. We see time and time again similar words being said as we find today: Anathema, you heretic, you are rejecting the First Commandment! And yet, it is they who deny the First Commandment – for how can you honor God if you do not honor his works among the nations? The Spirit blew as it will so that even among pagans we can find great prophets of God. Who are we to deny God among the pagans, to turn God into a tribal God, instead of the one God over all whose love has been gently guiding all the nations of the world? Yes, people can and did misconstrue what they were taught. Many nations took what they were given and abused it, turning away from the fullness of what was revealed to them. Nonetheless, all of this can also be shown to happen within the Christian faith as well, where the Bible is often misunderstood and abused by its readers. We do not disregard the Bible due to such abuse, and so we should not excuse ourselves from exploring the wisdom of the nations just because it could be abused.
St Jerome, like some bishops today, was asked why he was defiling the Church by quoting pagans. “You ask me at the close of your letter why it is that sometimes in my writings I quote examples from secular literature and thus defile the whiteness of the church with the foulness of heathenism.” First he pointed out that even Scripture does this – we have Moses, the prophets, and the Apostles all engaging and, often approving, the wisdom of pagan sages:
For who is there who does not know that both in Moses and in the prophets there are passages cited from Gentile books and that Solomon proposed questions to the philosophers of Tyre and answered others put to him by them. In the commencement of the book of Proverbs he charges us to understand prudent maxims and shrewd adages, parables and obscure discourse, the words of the wise and their dark sayings; all of which belong by right to the sphere of the dialectician and the philosopher. The Apostle Paul also, in writing to Titus, has used a line of the poet Epimenides:“The Cretians are always liars, evil beasts, slow bellies.” Half of which line was afterwards adopted by Callimachus. It is not surprising that a literal rendering of the words into Latin should fail to preserve the metre, seeing that Homer when translated into the same language is scarcely intelligible even in prose. In another epistle Paul quotes a line of Menander:“Evil communications corrupt good manners.” And when he is arguing with the Athenians upon the Areopagus he calls Aratus as a witness citing from him the words“For we are also his offspring;” in Greek τοῦ γὰρ καὶ γένος ἐσμεν, the close of a heroic verse. And as if this were not enough, that leader of the Christian army, that unvanquished pleader for the cause of Christ, skilfully turns a chance inscription into a proof of the faith. For he had learned from the true David to wrench the sword of the enemy out of his hand and with his own blade to cut off the head of the arrogant Goliath. He had read in Deuteronomy the command given by the voice of the Lord that when a captive woman had had her head shaved, her eyebrows and all her hair cut off, and her nails pared, she might then be taken to wife. Is it surprising that I too, admiring the fairness of her form and the grace of her eloquence, desire to make that secular wisdom which is my captive and my handmaid, a matron of the true Israel?
Jerome then described the way various Christians have used pagan wisdom. While many of them used it as a line of defense for the Christian faith, Jerome says that we should not limit our use of such wisdom in apologetics:
You must not adopt the mistaken opinion, that while in dealing with the Gentiles one may appeal to their literature in all other discussions one ought to ignore it; for almost all the books of all these writers— except those who like Epicurus are no scholars— are extremely full of erudition and philosophy. 
Scripture and the saints have used pagan wisdom – therefore, if one is going to charge their use as being an abandonment of the faith, worthy of condemnation, Scripture and the saints would have to be condemned. And to do that, of course, one ends up creating a new religion, one which is not the historical Christian faith but something different. This is the irony of such arguments: to try to “preserve the faith” many end up, through their ignorance and pride, abandoning it, suffering the anathema which they give to others. Indeed, who in their right mind makes an anathema without the spiritual authority to do so, to declare churches and leaders who explore the wisdom sown throughout the world as liars and their churches to be abandoned? Who, among Catholics, give themselves the role of a bishop to make such declarations? Such egotism! Such prelest! Let them heed the advice of the God-bearing Saint, Ignatius of Antioch before it is too late: “He, therefore, that does not assemble with the Church, has even by this manifested his pride, and condemned himself. For it is written, ‘God resisteth the proud.’ Let us be careful, then, not to set ourselves in opposition to the bishop, in order that we may be subject to God.”
 Cited in: J. Robert Wright, ed. Ancient Commentary on Scripture: Old Testament IX. Proverbs, Ecclesiastes, Song of Solomon (Downers Grove, IL: InterVarsity Press, 2005),199.
 Does not the great Dies Irae say as much:
Dies iræ! Dies illa
Solvet sæclum in favilla:
Teste David cum Sibylla!
 See Nicholas of Cusa, De Pace Fidei, I. for a representation of this fact in Christian literature.
 St. Jerome, Letter LXX in NPNF2(6): 149.
 Ibid., 149.
 Ibid., 151.
 St. Ignatius of Antioch, “Letter to the Ephesians” in ANF(1): 51.