I've gone over this before:
1) Assuming that The Prophet is NOT Inarius, that means that we now have TWO angels that went amongst the nephalem in secret with a religious theme, training them to battle the forces of Hell, and referred to themselves as The Prophet. E.G a A.U/ 100% duplicate of the Inarius character, except this new Inarius might be free.
That is absolutely BS and idiotic. 110% pure, undiluted stupid. Just think about it for a minute.
2) This 'The Prophet' IS Inarius and I would not count on them coming up with a good reason or plot pertaining escaping Hell or w.e, instead they just retconned his character.
There is a 50-50 chance between them. Option #1 should never, ever, at all even possibly be considered when it comes to stories but I honestly can't tell here.
First off, i didn't notice a "religious" theme with the Eirena's prophet, if i missed it, please correct me
Secondly, since Angels are prohibited by law to directly interfere with the mortal world, its more than possible that other Angels who wanted to help them disguised themselves to avoid detection from both Heaven and Hell, so two mysterious mentors trying to help mortals defend themselves agains the coming darkness 1500 years apart is far from "110% pure, undiluted stupid
As for the name "prophet" I'll admit it's hard to believe a coincidence considering Blizzard named both, and i doubt it was completely unintentional. But on a more realistic side, its like saying 2 people sharing the same nickname MUST be the same person.
Hey look, a Theory #3: A lesser Angel(or a small group of them) wih a similar mindset as Inarius continued to watch over mankind after the end of the Sin Sars, 1500 years later, one of them goes to sanctuary, disguises himself as "the prophet" in honor of Inarius's sacrifice, finds and trains mortals with promising powers, and send them to the future where they will be most needed.
hey look, a valid theory that doesn't involve Inarius as the prophet, it must be "absolutely BS and idiotic .110% pure, undiluted stupid