It is my understanding that in order for a baptism to be valid, a trinitarian formula must be used. My question the is, when John the Baptist was baptizing, whose name was he baptizing in? I doubt it would be the trinity, because it had yet not been revealed. Would this make Jesus’ baptism invalid?
None of John’s baptisms valid in the sense of being sacramental. They were baptisms of repentance and were purely symbolic. But even if they were sacramental, the baptism Jesus received could have no effect since sanctifying grace has its source in him. It would be something like striking a match to ignite the sun.
Fr. Vincent Serpa, O. P.