One of the most basic and existentially engaging of all questions has to do with the possibilities for human happiness and fulfillment on the one hand, and misery and loss on the other. Christian theology has returned the striking answer that the possibilities are truly extreme. According to Christian theology, the world is such that humans can experience perfect happiness, delight, and satisfaction, and do so forever. Indeed, that is just what human beings were created for: an eternal relationship with God that will fulfill humankind's best potentialities and aspirations. But the flip side of this is also possible—namely, that people may fail to achieve this relationship with God and thereby come to utter ruin and misery, a condition that is also believed to be eternal.

So understood, heaven and hell have provided an important moral source for European...