"If you're up to it, I'd like to see a list of your favorite non-atheist, brilliant writers and artist of this 'atheist age'. It seems like this fella never picked up anything by JPII or Benedict if he thinks that there are no more mighty scholars today. I'm sure you can name many more excellent non-atheist writers, but are there any current, non-atheist composers or artists that are worth checking out?"Well call me on it why don't you...
First, I should confess that I don't keep up with the current art and music scene a great deal. It is, frankly, a lot of work to sort through it all, and since I don't live in New York I couldn't see much in person anyway. So I'm not necessarily the best person to ask this question. I'd certainly like to hear from anyone among our readers who is more up on things than I am.
Second, I should clarify the the scope of my assertion. While I certainly think that artists, musicians and writers who are atheists have produced some good work, what I think a materialistic worldview is not good at producing is "great" art in the sense of art that has a scope beyond the confines of strictly interpersonal drama. Atheism can produce a Camus or a Picasso or a Sartre, but not a Milton or a Dante or a Michelangelo.
So, in regards to writing: Letting myself stretch back a bit to the mid 20th century, I'm pretty sure that one of the clearest "greats" from the century was T. S. Elliot. Some writers you're not sure will stand the test of time, but I'd put a fair amount of money of Elliot remaining in the canon for some time to come.
Going out rather more on a limb (and some may consider this selection low brow) I think that Tolkien's work will also stand the test of time. Aside from that, though, I'm going to leave the question of novels aside for now. I'm not as up on 20th century novels as I should be (I have suspicions that Greene and Waugh would figure in a list, but I won't go farther than that) and although there's been a tremendous output of novels over the last hundred years, I'm not sure any of it will unseat Dostoyevski in quality of writing and depth of vision. I'd lean towards the idea that he continues to hold the field in regards to the novel.
Dealing with more modern writers, someone I'd like to read more of is Polish/Lithuanian poet Czesław Miłosz , who was certainly a Catholic of sorts in regards to his artistic vision (after a youthful communist/atheist period) though how good a one in practice is a matter best discussed between him and his creator. (Interesting article about Miłosz here.)
As I said, I'm not terribly up on current composers, but one interesting one is Morten Lauridsen. I do not honestly know if he is religious at all, though he composes a fair amount of sacred music, and with (I think) more artistic sincerity than say Leonard Bernstein.
If there's someone out there who can speak to the question in regards to art, I honestly don't feel equal to it. I just don't keep up.
Though one thing does occur to me in regards to both art and music:
I think that the fragmentation of styles, breakdown of established forms, and (in the case of the visual arts) the willingness to declare literally anything to be art has actually made it rather harder to identify anyone in particular as excelling. Creativity often works best within the boundaries of a certain degree of limitation. (Even revolutionary innovation can only take place within an established order -- not chaos.) As such, I think it's probably harder to recognize who is truly brilliant in the current art scene -- because so much of what is out there is (quite frankly) intellectualized nonsense.