There is an approach to the Christian life that I find particularly tiresome. It is that emphatic cheerfulness in which all must take part, that demand that you will be joyful. But Christian joy is in fact a great part of our faith. In a few years we will mark the fortieth anniversary of a relatively obscure Apostolic Exhortation by Pope Paul VI, Gaudete in Domino, “Rejoice in the Lord” (1975). In anticipation of that anniversary, let’s look at some of his insights about Christian joy.

First and foremost, the pope underscored that true joy is internal. Like charity, it is not overbearing. He noted the need to teach people “how to savor in a simple way the many human joys that the Creator places in our path.” He then...