This book is a very good summary of Lewis’s writing, though organized by theme, not by the work: reasons for Lewis’s success, reasons to believe, what God is like, who is Christ, miracles, faith and reason, rivals of Christianity (little on Islam, by the way), Christian living, prayer, death and beyond.
I wrote down this passage (27). “[W]e can reject belief in God only at the cost of rejecting all fundamentals of human life — our hopes of satisfaction for our ‘infinite longings,’ our moral certainties, and finally reason itself” (good summary of chapter 2, “Reasons for Belief in God”).
And I made this note about “heaven as a bribe” (123-24): Purtill suggests that Lewis didn’t like this as a prime mover toward Christianity; my recollection is that he was okay with, at least, Pascal’s Wager (and, besides, God and Christ certainly didn’t hesitate to point to Hell and Heaven as motivators). But in any event the discussion suggests two reasons in favor of Pascal’s Wager: (1) by acting virtuously, we may become the mask, and there’s nothing wrong with that; and (2) this is not really a bribe in the usual sense of the word because fearing God and acting as He wants us to is itself virtue (cf.: it’s different to offer a bicycle for a good report card, versus telling you daughter that she’ll enjoy Greek as she learns it).