Turns out that being antagonistic toward Christianity is literally part of my cultural heritage
I was reading up on the history of the Indigenous group I'm a part of and I came across a text about the history of missionary work in my people's territory and I've never been more proud of my Indigenous heritage.
One of the earliest recorded cases of missionaries entering Nambikwara land was this American couple from the "Inland South American Missionary Union". Failing to garner any interest, they left in '27 and returned in '29, at which time they were attacked and the husband and their son were killed. The woman went back to the States to raise more money to try again.
Since 1930 there were Catholic priests who set up a school in Nambikwara land with the goal of making the locals literate in Portuguese and converting them. The school was tolerated and had students, many of which even became priests, but they only did so in order to learn the language and understand white people's ways to report back to their people, with no intention to ever evangelize to anyone back home.
A "know thy enemy" covert mission, basically.