"The Platonic strain entered Christian thinking early on, not least with the phenomenon known as Gnosticism. Since the Gnostics have been making something of a comeback recently, a word about them is appropriate. The Gnostics believed, like Plato, that the material world was an inferior and dark place, evil in its very existence, but that within this world could be found certain people who were meant for something else. These children of light were like fallen stars, tiny pinpricks of light currently hidden within a gross material body. Once they had realized who they were, though, this knowledge (Greek gnosis) would enable them to enter into a spiritual existence in which the material world would no longer count. Having entered upon that spiritual existence, they would then live by it, through death, and into the infinite world beyond space, time, and matter. 'We are stardust,' sang Joni Mitchell, plugging in to this millennia-old mythology, 'we are golden; and we've got to get ourselves back to the garden.' The Gnostic myth often suggests that the way out of our mess is to return to our primeval state, before the creation of the world. In this view creation itself is the fall, producing matter, which is the real evil. I hope it is clear both how deeply and thoroughly it diverges from it.
Though most people in today's world have probably only a sketchy idea of Gnosticism, assuming they've heard of it at all, it has been argued with some plausibility that some elements of it- and Gnosticism is always an eclectic phenomenon- are found in some of the seminal thinkers and writers of the last two hundred years in our culture. The writer and playwright Stuart Holroyd, himself an unashamed apologist for Gnosticism, lists Blake, Goethe, Melville, Yeats, and Jung among others as representing this stream in the modern West, and through their insights have often been cross-fertilized with other types, he has a point that should not be ignored. Basically, if you move away from materialistic optimism but without embracing Judaism or Christianity, you are quite likely to end up with some kind of Gnosticism. It should be no surprise that certain elements of the Romantic movement, and some of their more recent heirs, have been prone to this. The discovery of the Nag Hammadi scrolls (a library of Gnostic texts found in Upper Egypt) has in our day fueled a desire to reinterpret Christianity itself in terms of a supposedly original Gnostic spirituality that contrasts sharply with the concrete kingdom-of-God-on-Earth announced by the Jesus of the canonical gospels. Travel far enough down that road and you will end up with the blatant and outrageous conspiracy theories of a book like The Da Vinci Code. But there are many who without going that far now assume that some kind of Gnosticism is what genuine Christianity was supposed to be about.
Most Western Christians- and most Western non-Christians, for that matter- in fact suppose that Christianity was committed to at least a soft version of Plato's position. A good many Christian hymns and poems wander off unthinkingly in the direction of Gnosticism. The 'just passing through' spirituality (as in the spiritual 'This world is not my home, / I'm just a' passin' through'), though it has some affinities with classical Christianity, encourages precisely a Gnostic attitude: the created world is at best irrelevant, at worst a dark, evil, gloomy place, and we immortal souls, who existed originally in a different sphere, are looking forward to returning to it as soon as we're allowed to. A massive assumption has been made in Western Christianity that the purpose of being Christian is simply, or at least mainly, to 'go to heaven when you die,' and texts that don't say that but that mention heaven are read as if they did say it, and texts that say the opposite, like Romans 8:8-25 and Revelation 21-22, are simply screened out as if they didn't exist" (Surprised by Hope, pp. 88-90).