I didn’t get wet and I remained a Protestant. Amazing how handy those bridges are.
Since the river runs through the city, it is hard not to cross it when navigating Rome. This makes me wonder why the phrase is supposed to signify converting to Roman Catholicism.
This answer likely makes the most sense:
I don’t know where the phrase was first used, but it’s based on the geography of Rome. St. Peter’s Basilica & Vatican City are located on the opposite (west) side of the Tiber River from classical Rome (on the east) with its famous seven hills, Colosseum, Forum, Pantheon, Imperial Palace, Circus Maximus, and whatnot.
I would guess part of the idea in the language is that a Gentile crosses from paganism (represented by classical Rome) to Christianity (represented by St. Peter’s) through the waters of baptism (represented by the Tiber). Of course, not everyone who now “crosses the Tiber” was a pagan before doing so. Some are Christians, some are Jews. But I do think it’s a possible dimension of the metaphor.
But given the way that Roman Catholicism incorporated pagan philosophy (read Aristotle), does this make sense?
Old Life 