Why do you think that nobody shared your theology for the first 1500 years after the time Christ walked on the Earth?
You're sure that NOBODY did?
Or is t possible that there's just no record of it because the Catholic church obliterated it?
But I'll take a shot anyway.
Because Satan send in false prophets to teach that we're still under the law and people who didn't know their Scripture believed it.
Didn't Hebrews 11 address this??
If not...