As a nonparent, I stand in awe of parents. Our friends save for years to bring their children to Colorado, then spend thousands of dollars on the vacation of a lifetime and get little apparent return on their investment. The 10-year-old wants to play video games all day. The teenager sulks in the back seat, plugged into a portable CD player, head buried in a sports or fashion magazine, refusing even to glance at the glorious views outside the van window.

Younger children squabble about who gets what seat, feign motion sickness at every curve, and whine about how much time they must spend in a car. It's too cold for a picnic—or too hot. Why do we have to hike this stupid trail? I thought we were supposed to see wild animals—where are they? Can't we just stay home and watch a movie?

Amazingly, these reactions do not faze the parents. They are well-accustomed to shelling out dollars, prodding their children to get dressed, scraping uneaten food off the plate, cleaning up messes, and receiving in return reactions ranging from diffidence to sullenness. As parents, they understand this is part of what parenting is about.

The self-sacrificing, servant aspect of the Christian life has many parallels to parenthood. Every person feels a "cry from the heart" to serve those weaker than ourselves, says Jean Vanier, founder of L'Arche homes for the profoundly disabled. For many people, parenthood satisfies this need. Others—like Vanier the priest, like Jesus himself—seek to serve the poor, the lonely, the forgotten, the sick or disabled, in response to this cry from the heart.

The New Testament contains many passages directed to "parental" instincts. Gradually, gently, the writers press their readers to move beyond self-fulfillment. For example, ...