Communicate to the people that Tlazolteotl is evil and Toci is good.
evil vs. good?
The Catholic priest imposed his religion onto the Nahua people by having the tlacuilos help communicate Catholic beliefs. Tlacuilo artisits were often times noble-born males that painted and wrote nahuatl writing.
The priest explained his new definitions of the goddesses Tlazoteotl and Toci to the tlacuilos, and it was their job translate it into nahualt writing. They had to help the Nahua people understand the Catholic concepts of sin, heaven, and hell.
Tlazolteotl was taught to be only evil and Toci was good. This was to teach the Nahua people about sins and saintliness. By manipulating the meaning of these goddesses, it was the first step taken to help further introduce the Catholic religion to the people.