After his reluctant conversion, C.S. Lewis's life began to change. In his friendships and work at Oxford, his faith started to make a difference. But a phone call changed everything. When Lewis was invited to address the nation on the BBC about spiritual hope during WWII, he started to become the C.S. Lewis we know today. From then on, he would write book after book, letter after letter, and become the world spokesman for "mere Christianity."