in Catholicism, there are 7 holy sacraments. Baptism, First Communion, Reconciliation, Confirmation, Marriage, Ordination, and Last Rights. the church believes that these are moments when an individual makes a very direct and personal connection with God and it is not to be taken lightly. in the strictest observation of these sacraments, there should be absolutely no photography what so ever, but we live in modern times and whoever presides over the ceremony will determine what will be allowed and what will not.
having been an altar server, receiving 5 of the 7 sacraments myself, and being a wedding photographer as well, i am not one bit surprised about the Priests reaction nor do i disagree with it at all. Marriage is a religious ceremony first and foremost, it is a privilege to be present during it whether you be a guest or hired to photograph it. in the eyes of the church, the only necessities are God, the couple, their commitment to each other and to God, and the ordained officiant. that's it.
now on the other hand, IF i were still a practicing Catholic, i might argue that i am practicing God's gift to me through my photography and that i am there to honor God, the couple, and the sacrament with my skills but in the end nothing trumps the sacraments.
regardless of all that, i still show the proper respect during religious ceremonies whether they be Catholic, Jewish, Hindu or whatever. that moment is not mine...it is God's and it doesn't matter if i prescribe to the doctrine or not.