The key problem was that – unlike non-Christians of the Old World, who could be assumed to have had the opportunity to learn the teachings of Jesus, and therefore to have actively rejected them – it was fairly obvious that the inhabitants of the New World simply never had any exposure to Christian ideas. So they couldn’t be classed as infidels. The conquistadors generally finessed this question by reading a declaration in Latin calling on all the Indians to convert before attacking them. Legal scholars in universities like Salamanca in Spain were not impressed by this expedient.
