By Jeffrey Blackwell/Memorial Church Communications

On a sunny fall morning, the bell in the steeple of Harvard’s Memorial Church calls worshippers to Sunday services and a flock of sleepy undergraduates, hurried graduate students and long-time congregants begins to file through the doors of the storied sanctuary.

In the midst of conventional University faces are the smiles, giggles, and eye-rolls of chatty young children in the herding tow of parents and grandparents. Each Sunday during the academic term the children, ages 3-15, take part in a...