Sentence:  Indians who were enraged and dumbfounded at the Spaniards' barbarity, <WSD>heathenhood</WSD>, and moral shipwreck. So really, you said, that means that if Christianity got there before the Spaniards, then what were the Spaniards doing there? 
Meaning of the word marked with <WSD> tags:  The state or condition of being a heathen.