Pope Francis has praised the "holiness" and "zeal" of an 18th-century Franciscan missionary he'll make a saint when he visits the United States this fall but whom Native Americans in California contend brutally converted indigenous people to Christianity.

Francis on Saturday praised the accomplishments and qualities of Rev. Junipero Serra during a homily at a Rome seminary training future priests from North America. The pope will elevate the Spanish native to sainthood in a ceremony in Washington, D.C. in Sept. 23, during his U.S. pilgrimage.

Native Americans have held protests in California, saying instead of being honored, Serra should be criticized for what they say is his role in wiping out native populations in a brutal campaign to impose Catholicism.

Francis says Serra defended natives against "abuses by the colonizers."