C.S. Lewis on what makes Christianity unique

During a British conference on comparative religions, experts from around the world debated what belief, if any, was unique to Christianity. They began eliminating possibilities. Incarnation? Other religions had different versions of gods appearing in human form. Resurrection? Again, other religions had accounts of return from death. The debate went on for some time until C.S. Lewis wandered into the room. “What’s the rumpus about?” he asked, and heard in reply that his colleagues were discussing Christianity’s unique contribution among world religions. Lewis responded, “Oh, that’s easy. It’s grace”