The correct answer to this open question is the following.
I would refute such claims today in the following way.
Spaniards conquistadors were ignorant men that only had the limited conception that its Catholic religion of the 1500s imposed on them. They only believed the dogma of their religious teachings in a period of time in Europe where if you did not obey what the church says, you were sent to burn in the stakes. The inquisition times.
So when these Spaniards tried to evangelize the Native American Indians, they automatically questioned, criticized, and negate all the precious culture of the Aztecs and other native tribes.
But as history has taught us, the pantheon, traditions, and mythology of these Mesoamerican Indians was supported in the belief of their deities and presence of Mother Nature in everything they did in their daily lives.
They professed their own faith and worked very well.
So when Spaniards asked about the brutality of the Aztecas sacrifices at the top of their pyramids, one has to wonder about the brutality the Spaniards showed when they massacred thousands of Indians or the hundreds they tortured.