The Mission (1986) on Netflix

It's the mid-eighteenth century. Unlike his predecessor who was murdered and crucified for his efforts by the people in question, Father Gabriel, a Jesuit priest, is able to gain the trust of the Guaraní to build a mission in their region, above the falls in the border area of Brazil, Argentina and Paraguay, so that he can bring the word of a Christian god to the Guaraní. Father Gabriel's predecessor's fate was not only because of the Guaraní 's mistrust of him, but their mistrust of the white man in general, they who had previously pilfered many native South American tribes for slaves. Someone who unexpectedly joins Father Gabriel's order in building the mission is Rodrigo Mendoza, a mercenary and slave trader, who is trying to pay penance and repent for some past actions, most specifically an incident involving his half-brother. Father Gabriel's work and the lives of the Guaraní are threatened with the arrival into the area of Cardinal Altamirano, who must decide on the fate of the mission based on the fact that the land on which the mission sits has been ceded by the Spanish to the Portuguese, who are open to enslaving the indigenous peoples as opposed to the Spanish who officially banned the practice despite the former work of people like Mendoza. Cardinal Altamirano will factor into the equation of his decision that the Portuguese may take action against the church as a whole if this one mission is not closed. Father Gabriel and the order have to decide how to proceed, with the possibility that he and Mendoza will end up on different sides of the fence. Mendoza has vowed obedience to Father Gabriel in becoming a priest but may have definite and extreme views based on previously being a mercenary and slave trader. Meanwhile, Father Gabriel wants to protect the Guaraní under the name of God, they who have converted and who are in this position largely because of him.