Clare Sestanovich: Faith in unconditional love can seem like the bliss of ignorance—a comforting story to tell ourselves. But I’m not sure that’s right. What the missionary understood, I think, is that this sort of love is in fact the most fearsome kind. If God loves you whether you’re in or out, good or bad, can you be sure he’s really there? The question is not only for the religious. Can we be sure of each other? Can we be sure of ourselves?