Well, there's the Bible. Namely the 4 Gospels, Both Corinthians, and Revelations. Those books alone you could read decades and not fully decode them. They're incredibly powerful, not just as a record of history, but in healing the heart and in learning to command intent. Promise you as soon as you turn to the first page, demons tremble in fear.

Everything by Nietzsche, in order. it's literally the Great Awakening for one man. Imagine critiquing and mocking Christianity your entire career only to come to the conclusion that without God life is meaningless and He created us in His image so we could act in His image. Determinism, Uberman, the complete rebuking of nihilism and lukewarmness (which is what Jesus commands)

I do find value in the rest of that brand of philosophy. Plenty of relevant concepts in Jung, Kafka, and Kant.

Fiction (very little of worth out there in literary form)

Phantom Tollbooth by Norman Juster A Little Princess by Frances Burnett Anna Karenina by Leo Tolstoy Three Musketeers and The Count of Monte Cristo by Alexander Dumas Ender's Game and Xenocide by Orson Scott Card

I picked these not just for their amazing stories but for the themes and quotes so incredibly relevant to us as Christians, anons, frens, and pedes

also 1Q84 by Haruki Murakami

I haven't read this one but my wife raves about it and the original cover of the book is a gigantic Q. She's always suggested I or someone else well versed in Q read it for decodes (because off what she's told me, there's a lot)

The rest of what you need isn't in books. It's in anime and video games. I'm not joking, but if opera and theatre defined one era of fiction, the "Great American Novel" defined another, hundreds of years later the interactive and visual fiction of today will be seen as the high art it actually is.