I discovered that everything happens in cycles. Here is a quote from Wiki:
"The two most famous conquistadors were Hernán Cortés who conquered the Aztec Empire and Francisco Pizarro who led the conquest of the Incan Empire. They were second cousins born in Extremadura, as were many of the Spanish conquerors. Catholic religious orders that participated and supported the exploration, evangelizing and pacifying, were mostly Dominicans, Carmelites, Franciscans and Jesuits"
Catholics and other Christians openly supported conquering and invasion of other civilisations, by force.
Now, we have IS, and we don't like it!
Are all of humanity simply barbarians?