They were successful for numerous reasons. One is that there were already a lot of Europeans there who were willing to help in the spread of Catholicism. Another is that they were mostly experienced in military conquest so if anyone actually tried to oppose the spread of Catholicism from the natives, they would be punished severely since no one could oppose the missionaries.
Establishing a national bank.
he wanted to create a place where he could practice his religion freely
The racial ambigiuty problem because of those mexicans entering the border