This is a bit of a ramble through my inquiry.
Back in the 19th century one thing to say was that Christianity was spoiled by Greek philosophy. It can be viewed as a ploy to eclipse doctrine. Doctrine requires careful philosophical thought, specially advanced and difficult doctrine such as that done in the fourth and fifth centuries, and so it is not unusual to see philosophical underpinnings. The idea seems to have grown on people that Greek thought polluted the pure stream of Christianity, making it doctrinal rather than more purely ethical and sentimental. The fight back seems to have left a residue of those who want to say Christianity was not polluted by such outside influences. As a result, some wanted to minimize the influence of Greek thought, surrendering it as a pollutant, but not willing to say it had polluted orthodox Christianity. So the push back on the notion of Greek thought as a pollution was not to say it was not a pollution, but to say it was not that big of an influence, or to say it was what caused heresy but not orthodoxy.
Here’s my thought: ancient philosophy is good philosophy. It is not perfect philosophy, and they had their wrangles and schools, but in general philosophy was done well, careful thought was thought, distinctions were achieved. In short, good and reliable thinking on epistemology, metaphysics, ontology, ethics, and such was achieved and available, even about theology in the broadest sense, though not in any complete sense.
These speculative systems of philosophy were done by thinkers who had no real theological or philosophical inhibitions. They followed questions to the problems the answers raised, and continued along as far as they could. They argued, debated, read, commented, were influenced, diffused, discussed, and emended. Whole speculative systems were achieved, by free inquiry and by great thinkers, and these were available with all their tools, distinctions, insights, problems, etc. Ancient philosophy, in other words, was a great achievement. And for me the greatest of these was not Aristotle as many seem to think, it was Plato. That may be debatable. The truth is that for most purposes either will do, but for me. And it was in Plotinus that Neoplatonism made the grand conclusion of pagan philosophy, full of excellent insight, besides all the good that went before.
The church fathers had a predilection when it came to philosophy: Plato. Not Aristotle, though he was present. Stoicism was a strong influence because of its ethical rigor too, but rejected for its materialism. Plato, however, was mental, spiritual, and congenial to the early church. Read Clement, read Irenaeus, read of course Origen and Augustine and the Cappadocians. Look at the tremendous influence of the ingenious Pseudo-Dionysus.
Of course, you have comments in which these fathers distance themselves (Augustine, for example, sours gradually over time). Because philosophy was a pagan product, and the Christians had to distance themselves from paganism, there are going to be disparaging comments. As the fourth century went by, as paganism was more obviously in collapse, as Julian tried to give a theology to paganism by using Iamblicus’s degraded Neoplatonism, of course Christians took an even dimmer view of what was philosophy around them.
So there are at least three things that need to be taken into consideration regarding Christian statements of hostility toward philosophy. One is that they were thinking of it as a religion, because that’s how seriously it was taken. It was the closest thing to theology the pagan world ever developed, after all. Obviously Christians would want to distance themselves from any appearance of syncretism in a pagan world. A second is that as Christianity began to flourish as the dominant religion, pagan philosophy was being appropriated to give coherence to a failing paganism, and no Christian wanted to support that. And a third is that these Christian thinkers were so much a part of their intellectual milieu that they believed they were really putting distance between themselves and the pagan philosophies when in fact they were only quibbling.
For example: Plato believed in reincarnation. How essential is it to believe in reincarnation to be a Platonist? I don’t think it is essential to what Platonism is, but obviously Plato was big on it. The early Church had to reject that doctrine because we believe in the resurrection, we believe in death and after that judgment which is subsequently unending. Another example: Plato believed the archetype of man had wings, Origen said Plato was wrong. How much distance does this really put between them, however?
Which brings up the problem of definition. What is Platonism anyway? If I’m going to say Christian Platonism, what do I mean by each? Why is it necessary to qualify Christianity?
At one point I don’t think it would have been necessary. The first 1000 years of Christianity were philosophically Platonic. What happened in the 13th century was the accommodation to Aristotle that Albertus Magnus and Thomas Aquinas effected, and after that Christianity, when it consciously appropriated Platonism, did so quite differently. But for 1000 years Christianity was adjusting and assimilated Platonism. It had Neoplatonic conceptual tools, it had assumptions that came from classical philosophy (divine simplicity, for example) and it incorporated these things. (It internalized Platonism because Plato was right about many things, not because it was beholden to him for the construction of what it came to be).
How could it do that? It could do that in the sense that it was correct to do that since Scripture does not provide philosophy, it assumes it. Just as it assumes Hebrew and does not provide introductory courses, grammar books, or lexicons. The same: you have to be able to think clearly, to be able to think abstractly, to make fine distinctions, to use valid logic and so on. These things are those which classical philosophy provided.
In the sense of how it happened, it happened as Christianity moved away from Judaism. Christianity at first was one of Judaism’s many and puzzling factions. It was another pesky Jewish thing. As Christianity grew and sorted out internally its relationship to Israel, as Rome soured on the Jews and finally drove them out of Jerusalem, essentially ending any Jewish Palestinian identity, the church had to leave its wet-nurse. That the training going on was rudimentary, that a religion of the wider world needed to turn toward this wider world and stand on its own, gives us the moment of the apologists. They being to reason with the wider world in the wider world’s terms: they have to. Justin Martyr called himself and dressed as a philosopher, and was a Platonist in so far as he was a thinker at all.
The gnostic moment came and it saw two solutions. One was northern and Roman. Irenaeus refused the incoherence by affirming the church’s public and accessible teaching, proper order, and coherent, original doctrine. The southern solution was Alexandrine. Clement was less objective, and therefore harder to appreciate than Irenaeus. He claimed to be the true gnostic. What the gnostics wanted, something deeper, something with more wonder, with more thrill, he acknowledged, up to a point. The gnostics not only got Christianity wrong, they also got philosophy wrong (see Plotinus on that). Clement realized they got both wrong and wanted a solution that got both right. Christianity needed more rigor of thought, more deepening of insight and understanding, better teaching. Clement actually believed that as God made a covenant of law with the Jews for salvation, he made a covenant of reason with the Greeks for salvation. Now this idea needed to be improved on, but at the time, it had an effect.
Clement created an atmosphere in that place of heady intellectual fogs and mists in which Origen could afterward exist: critical but positive about philosophy, maintaining coherence while achieving deeper understanding. Clement admired Plato. Irenaeus, Eric Osbourne assures us, was a Platonist. Origen, if you read his student’s panegyric on his training, used a Platonic approach to training, and is to this day classified as a Neoplatonic philosopher. The Christian explanation of evil, at least in the early church and through the Middle Ages, is Platonic. The Christian scale of values, spiritual over material, invisible over visible, is Platonic (it is just right thinking, but Plato helps us see how it is, and why it is). Early Christian accounts of the fall from Origen to Gregory of Nyssa are remarkably Platonic. Participation, such an important concept for Athanasius against Arianism, is unambiguously a Platonic way of thinking about things that Christians found useful for explaining things, and even Aquinas retains it.
At the same time the early church modified what it was getting from Platonism. Is the body a prison from which one seeks to escape? In Origen the fall results in our being subsequently embodied. It is part of the punishment. In Athanasius, the body is not necessarily a prison, but most of the early church’s piety involved asceticism, and this asceticism was in an effort to prevent the body from becoming a prison, blinding the Christian with lower pleasures and baser desires to higher, spiritual pleasures and desires. So Platonism was adjusted and modified.
Christianity was not adjusted and modified; Platonism was. But that which was adjusted and modified had a source. There were things Scripture assumed, and Platonism supplied assumptions, among other things. How, for example, do you think about the spiritual realm? The Platonists were practiced at dematerializing thought in order to do this. I am pretty sure that divine simplicity was simply assumed from ancient philosophy, that it did not arise from Scripture itself but instead arose from natural theology (see Aquinas).
If you want to understand the early church on the interpretation of Scripture, especially in the use of allegory, you should understand Platonism. Origen figured out how to approach Scripture as the mind of God. Allegory, one might say, is—let us take the example of a stone, an object mentioned in Scripture—how one finds out what God thinks about stones. They are not just natural phenomena, they mean something, there is a reality underlying all these instances, an importance to them that God knows. And it has to do with us and our salvation. You can explain early Christian exegesis without recourse to Platonism, of course; but if you understand Platonism, you will understand far better.
I am not saying you have to be a Platonist to be a Christian, but I think a Christian can be a Platonist, and I think it ought to be a better known school of thought. A Christian Platonist is one with a critically appreciative attitude toward the philosophy of Plato as it descended to Plotinus and was then assimilated into Christianity. Once you have metaphysical realism, participation, an ontologically calibrated epistemology, the confidence in human reason, you have Platonism. You can see it in Eriugena in the 9th century, it is all over the 12th century, you’ll find it before, Anselm was one, and I think it comes out at the other end in Meister Eckhart.
What happens in the Renaissance is that Platonism is increasingly appropriated for the purpose of doctrinal minimalism, which is a weird inversion. In the early church it served for doctrinal maximalism, for clearer and more precise doctrinal formulation. But with Erasmus you see him availing himself of a Platonic scale of values to advance a Brethren of the Common Life approach in which ethics begins to eclipse doctrine (see a Kempis). With the Cambridge Platonists it is the same (they are the last of the Renaissance, in a way). These figures stand for a pre-modern philosophy in the midst of change, but also for a higher level of religious wrangling that will escape the acrimony of Puritan doctrinal confrontation. And there were no doubt more, but knowing about anything after the Reformation is not something I do a whole lot of yet. In the 19th century the Platonists were the modernists, with the exception of the pre-modern Platonist George Macdonald, that pal of Maurice the unclassifiable. (I’ve heard Shedd is of Platonic inclinations.) Same thing as with Erasmus and the Cambridge Platonists, the theological modernists, all admirers of Wordsworth. The appropriation of Platonism is dodgy. Why? I do not know.
And then you get C. S. Lewis. C. S. Lewis, Christian Platonist. It makes sense, doesn’t it?