They never left?....................
I know the drug lords have been doing a lot of this stuff, but it’s not an official religion. And if the US would go back to the pre-Obama days, when Bush really did do a lot to wipe out the drug empires and gave a lot of on the ground support, the modern savages wouldn’t have a lot of traction. The local population hates them but is scared of them, and the US isn’t giving much help with Stoner Barry.
However, in terms of colonization, Christianity brought enormous benefits to the native populations of both North and South America. Aside from not having to worry about getting your heart ripped out because you were an unimportant person but the head honcho needed your blood to water his pyramid, you got to live in a society of laws (Spain was incredibly bureaucratic, then as now) and while it may have been tedious, it certainly was better than having your heart ripped out.
Let the Apaches explain that. Just in passing, they were a horrible group and all the other Indians were afraid of them. In fact, many entered into treaties with the Spanish just to be protected from the Apaches.
Also, the Spanish did not demand that the Indians convert. The Indians, regardless of their tribe, were offered a treaty, and one of the conditions was that they listen to the preaching of Christianity. They didn’t have to accept it, but they had to listen to it to enter into the treaty. Most of them accepted it, but there were some, such as the Hopi, who listened to the preaching, didn’t accept the religion, but agreed to the treaty and lived in peace.