All the theological elements of the founding Christian narrative are mythical. They've been placed in a biographical format, which makes for the confusion since the biography of Jesus has become so iconic it might as well be allegorical (as Mark practically said it was).

There's no way to falsify the claim that "sins are wiped away." As for the claim that repentance is good for the soul, while Christianity popularized forgiveness, it didn't invent the concept.