My Year of Darwin 4/30/2014: Christians or slaves

"The fire, bed, and situation showed the dexterity of an Indian, but he could scarcely have been an Indian, for the race is in this part extinct, owing to the Catholic desire of making at one blow Christians and Slaves" Charles Darwin, Voyage of the Beagle. 

I guess by Christian, they imply a sedentary, agricultural people. So, I guess, it's not good enough to modify a culture's belief system but it is necessary to obliterate their entire culture.