Terrorist attacks in Brussels

And the Conquistadores in Central America were in response to Aztec violence?

a bit of a false equivalency. Separated by thousands of miles of rough ocean, it was difficult to rein in abuse. The question you are trying to equate was "Why didn't other Christians stop the Popes which blessed such actions (of the Crusades)?"

Antonio de Montesinos and Bartolome de las Casas were very brave whistleblowers who alerted the Spanish government and the Church of the atrocities. And upon hearing of it, they weren't happy about it at all, to say the least. They condemned the actions of the conquistadors. Quite different from the imams who shout "death to America"