Prescott wrote from primary sources. And God was very mercifull to motivate Cortez to christianize the craxy aztecs and uplift their whole civilization; risking life and limb and comfort. Sorry, but morality is the same throughout history as the conscience given to man is constant. If you think mass murder of innocents in the name of a god is not demonic then you need to wake up a bit. It was all motivated by the opposite of christianity...hate. The same hate that causes murders and violence today. You can try to sugar coat the aztecs religion but it just doesn’t work.
All historians use primary sources. The understanding of any historical subject has increased greatly since the 1840s. You should look into that. Maybe you should consider reading more than that one ancient book before you decide that you are an expert.
Naturally, Cortez became very rich in Mexico. He attributed his success to God and to his native mistress and translator, La Malinche (aka La Chingada, which means ‘what is f___ed’). She was one of twenty slavegirls distributed among the Spanish captains. Bernal Diaz del Castillo (the most important Spanish primary source, whom I have actually read) calls her D. Marina. He says that they couldn’t have done it without her. I think she did a lot to engineer the downfall of the Aztecs. She is a much more interesting figure than Cortez.
Lots of Christian fanatics have committed “mass murder in the name of a god,” including the Spanish conquistadors. Do you think that they are demonic? Who is sugar coating?
Popular morality is always changing. For instance, slavery was considered to be moral until people realized that it was immoral. Does that mean that everyone who owned slaves when slavery was commonplace was an evil person? In my opinion, no.
The farther south you went, the further you would stray from this truth and motive. But that would be another story of conquest and oppression.