I think the Roman Catholic church had enough power to ruin the Aztecs religion and enough manipulative ways to persuade them to believe otherwise.  While Cortes was on his was to Tenochititlan, he came across some natives and converted them immediately.  They became his allies in defeating the Aztecs.  In some of the literature I came across, a lot of the Aztecs thought the Spanish were Gods.  They had never seen people like this before and even their horses.  Cortes had a very powerful impression on the Aztecs which I think led to their demise unfortunately.  But, again, they were very technologically advanced.  They fought off Cortes for a while and the city was so magnificently built Cortes had a rough time knowing how to get around.  It's a mystery we will never know!  I would totally side with the Aztecs if I could change history.