Hunt managed to sell only a few of his captives before local Roman Catholic priests seized the rest--the Spanish Church vehemently opposed brutality toward Indians. (In 1537 Pope Paul III proclaimed that "Indians themselves are indeed true men" and should not be "deprived of their liberty" and "reduced to our service like brute animals.") The priests intended to save both Tisquantum's body, by preventing his enslavement, and his soul, by converting him to Christianity. It is unlikely that Tisquantum was converted, though it's possible that he allowed the friars to think he had been.
From Charles C. Mann's surprisingly good book 1491: New Revelations of the Americas Before Columbus. Tisquantum was the true name of Squanto, from grade school history lore.