I am hopelessly attached to Michael O'Brien's books.
His Father Elijah was the first I read, about nine years ago. I became a zealous fan, pushing it on everyone I know. I've since read all of his novels (and have reread most of them several times) and I've loved each one of them (though they are not all in the style or genre of Father Elijah.) I'm always saddened to reach the end of his books ... I don't like having to put him away on the shelf. I miss him when I'm between books.
He's a gifted writer and artist, (be sure to take a look at the Byzantine page ... it's exquisite), and if you haven't yet visited his website, StudiObrien, you're in for a feast.
Plan to linger with a cup of coffee.