The natives are capable of Morality or Goodness and very apt to receive the principles of Catholic Religion; nor are they averse to Civility and good Manners
Las Casas is basing morality and goodness off of their ability to assimilate to Catholic ideologies, seeing them less as their own culture with their own ideologies and understandings of morality and goodness, and more as sponges to absorb the more "civil" ways of living.
Those that arrived at these Islands from the remotest parts of Spain, and who pride themselves in the Name of Christians, steered Two courses principally, in order to the Extirpation, and Exterminating of this People from the face of the Earth. The first whereof was raising an unjust, bloody, cruel War. The other, by putting them to death
Las Casas denounces the Spaniards who act under the guise of religion to commit unjust acts against Native Americans.