Nope, not a priest (happily married). "Son" is a term some Southerners use to get the listener's attention when it is apparent the listener is having a hard time understanding what is being said. It is a regionalism, not a religionism (is that even a word?).
That is not quite accurate. The use of the term, "Son" is an attempt to establish a superior position in a relationship.
You have not done that, Junior.
If you were truly speaking Southern, the dialectizer would have said it like this:
Son, ah's probably one of th' mo'e devout Roman Catholics yo'll evah meet, an' ah's not terribly wo'ried about a-gonna meet mah Maker.