Religious claims post-Sinai have to be tested according to Deuteronomy 13. The Jesus of the gospels fails that test, adding and taking away from Torah while breaking its laws and leading people to idolatry. The religion that follows him is fundamentally flawed.
Every religion before Sinai was sincere darkness.
From the third generation of Adam, mankind went astray; it all started there.
Every religion after Sinai is the Deuteronomy 13 test.
Adam, Seth, Noah, and Abraham can all attest to the truth of HaShem.