Tony's father is none too excited about his youngest son becoming a priest. He would be much happier if Tony would follow in his footsteps, and that of his brothers, and adopt the roaming, nomadic lifestyle of the Marez clan. Tony's mother and father argue about his future early on in the story, when Tony has been shaken by witnessing Lupito's death:
"Be sensible!" my father stood up. "The boy has not even been through his Catechism. And it is not the priest who will decide when the time comes, but Tony himself!" He stalked past me. The smell of gunpowder was still on his clothes.
They say the Devil smells of sulfur.
Tony is still a young boy at this stage of the story, with much to learn, and is as confused as anyone is at that age. It is this sort of raw template that is Antonio that Ultima has to work with.
Antonio's mother is leaning towards him becoming a priest because she believes "the people need good leaders, and the greatest leader is a priest." Tony often feels pressured to fulfill his parents wishes, but he wants to determine his own identity.