Oldest Christian artifact north of the Alps found in a Roman tomb in Frankfurt

Weren't Romans famous for adopting whatever rituals or rites they happened across? Sort of a what-the-heck-may-as-well kind of attitude.

E.g. roman coins buried in little holes next to bronze age barrows that just happened to be next to trackways. "Looks like a ritual site! Maybe that will give me luck" and they push a coin or two into the sod, just in case.

My point: this may not have been the tomb of a 'deeply Christian' person of any kind. Just another thing to put into a grave, might help, can't hurt.