I live in the Southwest. Pueblo Indians, who live here in tribal communities, are usually baptized Catholic and identify with Catholicism as their faith. This is because the Spanish conquistadors invaded their land, enslaved them and demanded they accept the religious beliefs of the Spaniards, on pain of death, if they didn't. The Spaniards did a good deal of evil to these people. This is why there was a Pueblo revolt in 1680 A.D.

The Spaniards had the idea that God wanted them to spread their own particular faith. They were prepared to force this on the indigenous people of the American Southwest by any means, including a great deal of violence. Nowadays many of us believe that this was wrong. (Even Mother Teresa decided that the idea of forcing people to convert was wrong, and she often refrained from even preaching to the Hindus and Muslims that she worked with in India.) So why did the Spanish Conquistadors commit great violence against the Pueblo Indians, oftentimes to strip them of much of their culture and force Catholicism upon them? Were the Conquistadors mentally ill? I don't think so. I think they were acting in accordance with ideas that they believed in. They believed - ardently - that God let them conquer lands in the New World, so that they could "win souls" for Christ. Toward that end they enslaved native peoples and forced them to build many of the "mission churches" that one finds throughout the Southwest. Most of us now think that extracting such forced labor from enslaved people would be wrong . . . and would be an enactment of evil. Are we more mentally healthy than the Conquistadors? Do we possess better functioning brains? Not many people would claim that. The difference is that we ascribe to different ideas.

So, throughout history, people have engaged in activity that future generations would disavow as evil - not because these more modern generations had developed better functioning brains, or had purer souls . . . but because the systems of ideas that humans subordinate themselves to change over time. Ideology evolves.

In some old cultures, tribes offered human sacrifice to the sun. The Incas did this. I think that was an evil practice. Many would agree with me. I don't think this "evil" occurred because the Incas were all mentally ill or had dysfunctional brains. They were entralled by what we now regard as a very terrible idea. Ideas matter.