A canon lawyer breaks down the implications for parishioners who had a fake priest as their pastor for several months. Interesting stuff. Excerpt:
[W]hat of those Catholics who attended "services" or received what they thought were sacraments from this man? As one person put it, "does his Mass satisfy the Sunday obligation?"
To answer the question as posed, No, for such an action was not a Mass and thus cannot satisfy the Sunday obligation. Nevertheless, anyone who attends a ceremony honestly believing it was Mass, only to find out later that the event was a fake, is excused the obligation for that day. Moreover, one who reverently received a host "consecrated" by such a man commits no idolatry, for there was no intention to worship something known not to be Jesus, the Son of God.
As for the other sacraments, his baptisms would almost certainly be valid, for one need not be in Holy Orders to perform a baptism (CCC 1256). Confirmation, on the other hand, would be invalid (1983 CIC 882) and, because it is a "character-imprinting" sacrament that can only be administered by a priest (1983 CIC 845 § 1), it would have to be administered anew. Confessions, too, though not character-imprinting, would also be invalid (1983 CIC 965) . . .
