The islands were not always called the Marianas. Spanish navigators had known them as the Islas de los Ladrones, the Islands of Thieves, until the Jesuit missionary Diego Luis de San Vitores arrived to begin converting the Indigenous Chamorro people in 1668 and had the archipelago formally renamed in honor of his patron, the Spanish queen regent Mariana of Austria, whose support had funded the mission. San Vitores did not survive to see the conversion he began succeed. On April 2, 1672, he entered the home of a village chief named Matapang, a former Christian convert who had turned against the mission, and baptized Matapang's infant daughter without his consent, an act many Chamorro at the time believed involved a poisonous substance rather than a religious rite. Matapang killed San Vitores that same day, along with his companion Pedro Calungsod, a young Filipino lay catechist who had traveled with him. The Catholic Church later beatified San Vitores as a martyr, in 1985, and canonized Calungsod as a saint decades afterward, but the mission itself did not end with their deaths, Jesuit and later Spanish colonial authority over the islands continued and Catholic conversion became nearly universal among the Chamorro over the following century.
That conversion survived Spanish, German, Japanese and American administration in succession largely unbroken, and Chamorro Catholic practice today retains distinct local devotions and fiesta traditions tied to village patron saints, observed with an intensity that marks the Northern Mariana Islands as culturally different from the more religiously mixed profile of nearby Guam.