It is probably fair to say that after love, joy is the uncommon quality most commonly associated with Christian life. "Joy," wrote the biblical theologian G.G. Findlay, "is more conspicuous in Christianity than in any other religion." Others agree.
When in the 18th century Jonathan Edwards proposed signs to separate true religious experience from its counterfeits, the Puritan preacher recommended that we look for joy. It was, he held, the dead giveaway that God was present in someone's life. The Roman Catholic spiritual director Baron Friedrich von Hugel reminded us that the canonization process in his tradition required that we find joy in the lives of candidates for sainthood, or their causes would be poked full of holes. He quoted and approved St. Philip Neri's observation: "There is no such thing as a sad saint."
The Protestant theologian Emil Brunner wrote, "Joy is the feeling we have when we really are ourselves." Paul Tillich, in agreement, said, "Joy is nothing else than an awareness of being fulfilled in our true being." And Karl Rahner has written a splendid essay placing joy at the heart of the mysticism of St. Ignatius of Loyola, the founder of the Jesuit order.
I am embarrassed to say that for a good part of my life, I did not know the joy these people describe. Or, perhaps more accurately, I knew it as a child and lost its abiding fervor along the way. I was only recently surprised by joy, to borrow C.S. Lewis' phrase, and according to my experience, that is exactly how we are introduced (or re-introduced) to it—by surprise, and not by our own design.