There is a C S Lewis book that in some ways surpasses Mere Christianity. The Great Divorce. Sticks to the ribs better than 'Mere'.
I agree. "The Great Divorce" is an excellent book. It's an allegory about Lewis' view of Heavan and Hell, and after reading it I concluded that God gave C.S. Lewis a hefty measure of prophetic vision along with that great intellect of his, IMHO.