One of the first books I read when I became a Christian 33 years ago was Mere Christianity by C.S. Lewis. I imagine that most people reading this blog are familiar with Lewis’ writing, but if you aren’t, I highly recommend this book. Or, if you prefer good fiction, then you might want to begin with The Chronicles of Narnia.
All of his books have some very quotable lines. Here’s one of many from Mere Christianity:
If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world.
Note added: That quotation is put in its surrounding context in this post. Also, there is an interesting discussion in the comments below that I would encourage you to read. Comments on all posts are still open.