SAN ANTONIO — Long before a 98-year-old nun became the biggest star of the 2018 N.C.A.A. men’s basketball tournament, Immaculata, a small Catholic college outside Philadelphia, won the first three de facto national women’s basketball championships.

The Mighty Macs’ titles in the early 1970s, Bill Russell’s breakout success at the University of San Francisco in the 1950s and the presence of Villanova and Loyola-Chicago at this weekend’s Final Four are just three data points among many that prove an undeniable fact: In college basketball, Catholic schools have long punched well above their weight. The reasons stretch back a century — and, some would argue, to the New Testament itself.

“It is a real thing,” said Julie E. Byrne, a professor of religion at Hofstra University who studies American Catholicism.

As the Final Four coincides with Easter weekend, this phenomenon is as real as ever. Half the No. 1 seeds in this tournament were Catholic teams, as were eight of the 64 teams that made the bracket. Loyola is named for St. Ignatius of Loyola, the founder of the Jesuits, and has Sister Jean Dolores Schmidt as its chaplain and unofficial scout. Villanova is associated with the Augustinian Order. Both are still playing.