I agree about the importance of humility. The question is whether "mere Christianity" is an objective average or core creed, or whether it's a late-modern projection. Lewis says he learned to perceive this heart of the creed by reading more widely, whereas we might have imagined that doing so would have taught him to be more humble about the benefits of generalizing.

If so many Christians had such different interpretations of their faith, isn't the fundamentalistic reach for simplicity more likely a sign of ahistorical arrogance or impudence? Outside of the academy, Lewis was a popularizer, so one of his jobs was to simplify. That might have been a mere capitalistic imperative: he simplified to make money or to reach the masses.