Have you read Mere Christianity?

Mere Christianity
by C.S. Lewis is one of those must read books, it is an excellent presentation of the basics of Christianity, cutting right to the core of what it claims and making a rigorous defense of those ideas. It is is one of those books by Lewis along with The Great Divorce and The Screwtape Letters that I read through every so often.

Mere Christianity was originally a series of radio talks that C.S Lewis delivered on the BBC during World War II. Here is a video with an accompanying doodle of the start of Mere Christianity for your viewing pleasure.