How could the Spaniards arriving in the New World thoroughly be swayed by the new lands they've discovered, so much as to assimilate to the native cultures? If possible, even abandon their religion?
Mesoamerica and the Andes are rich and advanced, with Tenochtitlán being bigger than any European city (other than Istanbul?). While the rest of the Americas south of Georgia and north of the Rio de la Plata is harsh for people suited to a semiarid, temperate climate in Europe, making cooperation with the natives necessary.
The Spanish were in the most precarious position of all the colonizers, having the earliest technology and going to the most inhospitable part of the New World besides Amazonia, yet they were the most successful. Why was this?