For the past 49 years, since she joined the order of Religious Mary Immaculate at age 16, Sanchez has watched priests wash the feet of men on Holy Thursday. This week, Sanchez was before the altar herself at the nation’s preeminent Catholic shrine. She was the one removing her shoes and socks. And then the pope’s representative to America washed her feet.

This was the first Easter since Pope Francis decreed in January that priests can include women in the foot-washing ritual, one of the most moving rites of the holiest week on the church’s calendar. The change had already happened in some churches, but since Francis made it official, it is now spreading worldwide. ...