I was going to list some very different books, but as I read through the list, I found one that absolutely had to fit on the list.
1. East of Eden by John Steinbeck. Even in the middle of my rejecting religion, it spoke to me, and it wasn't until a few years later that I realized just how powerful that made it.
2. Les Miserables by Victor Hugo. I saw the musical first, but I love the book just as much, and I will defend it to whatever cause. I even stopped liking a character on a TV show for a while because she declared that she couldn't stand Victor Hugo's writing.
3. A Tale of Two Cities by Charles Dickens. First, French Revolution. I've had a slight fascination with it for years. Second, Sydney Carton. I feel a strange kinship to him, and it bothers me when people romanticize him into an ideal man. He isn't, and that's why I feel that connection, I think.