Since your other questions have been about Guns, Germs, and Steel, and since Diamond addresses this question in his book, I assume that this question refers to the book as well. I will base my answer on Diamond’s discussion in Chapter 3 of the book.
Technology helped overthrow the Incas because the Spanish had superior technology. Diamond mentions steel swords and armor as well as guns and other weapons in this context (p. 74). He also mentions the ships that brought the Spanish to the New World (p. 78). These technologies allowed the Spanish to come in contact with the Incas and helped them defeat the more numerous natives.
Religion helped defeat the Incas mainly because it helped to motivate the Spaniards. There are some who say that the Incas thought the Spanish were gods, but Diamond discounts that on p. 75. The Spanish had come to the New World in part to spread their religion. Individual soldiers were also motivated in part by the belief that their religion was superior to that of the Incas.
Disease helped to defeat the Incas because epidemics weakened them even before the Spanish arrived. Diamond says (p.77) that many Incas had died in a smallpox epidemic. Among these were the Inca emperor and his heir. This led to a civil war among the Incas which weakened them further. This weakness helped allow the Spanish to conquer them.
Literacy helped defeat the Incas because it allowed the Spanish to have more information than the Incas had. On p. 79, Diamond argues that the Inca emperor had very little information about the Spanish because no one could write reports to him as the Spanish approached. By contrast, Spanish literacy gave them information about the New World and its peoples. This helped convince the Spanish to invade the Incas’ territory.
Finally, governmental organization helped to conquer the Incas. Diamond argues on p. 78 that the Spanish had a better centralized government that the Incas had. The Spanish governmental system allowed Spain to get the money to build and equip the ships that brought the conquistadors to the New World. The Inca system of government was centralized in the person of the emperor. That hurt them when the emperor was captured and they essentially were without a leader.
To Diamond, each of these factors helped cause the overthrow of the Inca Empire.
Thank you so much!