Question: "Having read some Milan Kundera and his essays on modern literature and art has made me wonder the following -- Modern literature is said to go to the core of manhood or the existential experience of being a man, yet it clearly leads to (or amounts to the same thing as) what you would call, if I'm not mistaken, the demonic perspective. Can something/anything/nothing useful/beautiful/true be learned from this so called modernist world literature movement of the 20th century (Kafka, Joyce, Proust, Musil etc.)?"
My response: Yes, much that is positive can be learned from this genre of writing - so long as the metaphysical perspective of secular modernism is rejected.
The content is often profoundly insightful (e.g. Kafka, Musil, Proust), the quality of the prose may be superb (Joyce) and so on. It is also a document of the nature of the malaise, especially as it affected elites.
The main danger from this writing, and it is a very real danger, is in confirming people in their pessimistic, alienated, secular nihilism - making it seem inevitable, necessary, sophisticated...
My angle on modernism is therefore much the same as Colin Wilson - although he was not Christian.