Looking back on all that now, a sophisticated Catholic of the 20th century--post "Fides et Ratio" and post- the countless other affirmations of the essential compatability of science and faith--may be rather amused by what will strike him or her as a laughable religious naiveté. I mean, really, must one's beliefs actually be shaken to the core by the simple discovery that evolution may have occured, when science so patently would never be able to provide an account of how that evolution began (because we can only work with what we have evidence of in science: please don't bother us with speculations about the beginning of matter because that means reaching back to a prematerial time--if such a thing is even conceivable on scientific terms--for example). I mean, unless your entire faith is based on a fundamentalist literal understanding of the Bible; as "Dei Verbum" reminds Catholics, of course, "fundamentalism actually invites people to a kind of intellectual suicide". And here's where we see that happening at its finest. People saying: oh, well, the Bible doesn't describe evolution, so if evolution is true, the Bible must be false. Forgetting, of course, that the Bible may be taken as using a mythical genre in certain parts, a historical genre in others, etc, without a whit of its essential truth being taken from it.
I don't want to condemn the age, certainly. Many people did keep their heads, and it's interesting enough that the few scientists of the time who successfully integrated faith and their work were actually Catholic. Catholics having on the whole something of a horror of fundamentalism. Yes, even back then. I'm thinking in particular of Antoine Lavoisier, Louis Pasteur, Marie Curie. (Gotta love your French Catholics, even though American Catholics who have some sort of national guilt at not being quite Puritan enough tend to detest them Just for good measure. Can't like those Papists...)
Anyway, all of that is merely a long-winded explanation of the situation the Romantic authors of the early 1800s found themselves in. Instead of trying to genuinely reintegrate religious faith with the new, post-Enlightenment world, the panicked and threw out the faith aspect along with most of the rest of their generation (again, I'm judging these people in very gross generalities). Northrop Frye, in "A Study of English Romanticism", explains the conundrum of these artists very astutely in terms of the scientific discrediting of the age-old mythical stucture of the cosmos. That is, the symbolic notions of the geo-centric world, the heavenly spheres, the notion of Divine Right in law, etc, were knocked to the ground by Copernicus and his descendents. Notice that I said symbolic. Part of the problem here is people falling into suicidal literalism again. The myth isn't part of the Word of God, but it had explained it for so long that people began to forget that a myth is a metaphor. Never a scientific fact. A way, rather, of making sense of the more universal structures that aren't within science's realm at all.
Yet with that model "discredited," the Romantics weren't willing to let go of the belief that something must be more important than 1+1=2 or the law of gravitation. They reclaim the notion of faith, but now limit it strictly to being "poetic" faith, in which the subject-object distinction created between man and nature by both the Christian affirmation of man's divine telos and the rationalist "clockwork universe" model is collaped back into a neo-pagan reidentification of the workings of man's mind with nature itself. Nature mirrors man's mental workings because she is not merely a mediator, a symbol of divine truth (as the Christian worldview would have it), but is in fact the source of the sublime that works on his intellect. Access to the transcendent is thus achieved directly through communion with nature, and the "original sin" myth of Christianity (don't worry that I'm a heretic: I mean "myth" in the sense of universal explanatory structure that may very well be true) is replaced with the "loss of original identity" myth. (I'm drawing on Frye for this bit.) That is to say, man's fallen state is not characterized by propensity to sin, but by a self-consciousness that destroys man's innocent state of communion with the source of sublimity by bringing him to an awareness of the subject-object relation with nature.
Essentially, as Frye observes, the Romantics take the Christian myth, and redefine it so as to have a "faith" that is compatible with the new order, but which still combats pure rationalism. But I am at a loss as to see how this should help them much at all. What are they doing on the most basic level? Well, they take divine transcendence out of the picture and replace it with Nature. Thus the sublime is now at one remove from us instead of at two (even here, you'd have to be pretty heretical in your Christianity in the first place to believe that we only have symbolic access to God such that he would be two removes from us to begin with. After all, Catholics believe that we don't just see Him and talk directly to Him; we eat Him. But that's another story, since we're in protestant, often fashionably liberal, England here). This is patently unhelpful though, since there's still that first leap of faith to get over: why should nature be the source of transcendence any more than God? They respond to the alleged lack of rationality in Christianity by denying that reason has anything at all to do with access to the transcendent. It's all in the "imagination", or the "poetic genius," as Blake likes to call it. Really, that if anything weakens the structural backing of faith. Why in the world should it be a relief to us to say: oh, well, it's not supposed to make rational sense, you're just supposed to get a feeling of sublimity from Nature? This requires as much--in fact, a lot more--blind faith than Christianity at its best does. We'd prefer to say: "Well, here are a ton of fairly compelling reasons why you should believe that this is real. Yes, we can't ultimately prove them, because they have their sources in what cannot be empirically measured, but you know, your scientific empericalism takes a bit of faith (please see David Hume) too, so what are we concerned about there?
Basically, all of this is to say that the Romantics seem to think that Pantheism is the answer to the crisis of faith. If you have problems with religious faith, I can't see that you're going to solve those effectively with pantheism, however. The biggest argument in favor of their approach, in fact, is simply that they get away from the language of religious faith that was then in such disfavor. So they rather got themselves to be taken more seriously than some raving preacher might. (Can you imagine Blake* as a cleric of the Church of England?)
Nonetheless, once you look past the veneer of "we're different from the religious people because we want faith to be individual and sourced in Nature", the Romantics really do have a very weak foundation for their "religion of poetry". At least, if they want it to be a serious contender against the forces of rationalism. So one can see without much difficulty why it collapsed so soon into the darkness of the Victorian poetic crisis of faith. That particular crisis I will be writing a paper on shortly, so more might be posted on it later.
*Of course, Blake in particular (he seems to be the only one to consider the relationship of religious faith and poetic faith very explicitly) does have some very legitimate gripes against the conventionalization of faith via the general political correctness of adopting certain tenets of Anglicanism in 19th century England. His complaints about "right being wrong" and wrong being right are fairly justified. If only he had realized that the Catholics would heartily agree with most of his complaints, he might not have misidentified this conventionalization as a problem intrinsic in Christianity.