The reason why the Catholic priests and missionaries opposed secularization of mission lands were:
The Mexican government decided to engage in the secularization of mission lands to give back lands to Native Americans and this worried the Catholics who felt that self-governance would lead the Natives to going back to their traditional beliefs.
They also did not want to lose the over 20,000 Natives Americans that were working in their missions and providing important labor.
Find out more on the secularization of mission lands at https://brainly.com/question/20919422
#SPJ1