The Torah is one thing - and full of holes - but having stories going over a long period, some are bound to have some substance.
Some were also borrowed from other cultures, so that might be used to establish some validity (though erroneously if not backed by substance). Ironically, Christians dismiss those as merely pagan, which simply serves to render their beliefs even flimsier. That Noah was real but Gilgamish is pagan myth when Noah is based on Gilgamish basically, well, sinks that boat.
- sorry, I hadda.
The Gospels have zero evidence to them. Even some things, like the alleged custom of Romans releasing a prisoner to honor Passover have no foundation, and defies logic.
Constantine's use of Jesus for political purposes is known. It's not a rumor, not alleged, not revisionist, it is a fact that he did so to reinvigorate a decaying Rome. Plus he took a renegade cult and co-oped it, retroffiting it to serve his purposes. Turning their God into Sol Invictus was no big deal. Neither God, as we know, did anything to protest.
Incidentally, it is the fulfillment of Scripture (chicken & egg enters here tho) where Son of Jackal seated in Rome shall steal the religion of THE Chosen (Judeans) and call it their own (ROMAN Catholicism), but not before corrupting it beyond recognition, as they had done. Christianity is a Roman (and Greek and Iranian) Paganized corruption of Judaism. That's why it's not Jewish and Jews aren't Christians and Christians aren't Jews.