This is an autobiography of the early years of C.S. Lewis. It describes the process that took place in his conversion to Christianity.
Lewis stipulates that the book is part biography and part a tale of his conversion from atheist to Christian. Early on it appears that it is all biography. But, indeed, upon reaching the end you realize that Lewis has been setting the stage to describe his conversion.
He was raised as a literary intellectual. He developed into a young man that neither sought nor believed in a God. His self-reliance and atheism grew in parallel with his intellect.
Lewis was firm and confident in his belief of atheism. He actually went on an intellectual excursion to prove his position. It was during his journey to disprove God that he found Him. He did not have an instantaneous conversion to Christ from atheism. His conversion can best be described as a scholarly process. He went from self-reliance, to there WAS a disinterested creator, to there IS a disinterested creator to, that creator is a vengeful God, to that creator is a loving God, to that loving God sent Christ to reconcile us. This was a very academic process for him and took several years.
If you are looking for a good biography of Lewis this is not it. This book has more to do with his alteration. While he does offer many personal details of his life he only provides that information that paints a picture pointing to his conversion.