Which “Native Americans” are you talking about? There wasn’t a single group of them. There were tribes who were often fighting one another, wiping each other out, etc.

Some tribes allied with and helped the European settlers in exchange for their help against other tribes. There wasn’t this great animosity between all of them and all Europeans like you are imagining.

And there wasn’t any conspiracy among Christians to wipe people out. There were agreements made and broken on all sides. Some land was simply bought or traded for.

You also need to keep in mind that back then, a vast majority of the continent was simply empty, unsettled wilderness. Europeans had advanced technology and favored settling in place and constructing improvements like buildings and roads rather than being nomadic, and many were itching to leave Europe for the new world.

It’s natural for them to expand faster than the locals who were already there. It didn’t help that the locals were susceptible to the diseases they brought with them…