I know it's the basic nerd answer but personally I still gotta go with gnosticism
absolutely the funniest possible solution to christianity's internal contradictions
imagine trying to resolve the whole "christians say god is both ontologically good and infinitely powerful, so how can all this suffering exist" problem, but instead of concluding "god isn't real" or "christian doctrine isn't true" and leaving the church, you go "okay hear me out: Literally everything in the bible is factually true and correct, it's just that GOD IS THE VILLAIN"
10/10 galaxy brain theology. gets you killed by absolutely everyone in europe. directly leads to a bunch of really weird but highly respected japanese cartoons like 700 years later
I mean, hands down my favorite heresy is Christianity. You're telling me Moshiach, who is also G-d, and also his own son, utterly fails to restore the righteous kingdom and is in fact killed but comes back(?) but still doesn't really accomplish anything. Gotta appreciate the sheer audacity there
Continuing in that vein, my favourite heresy is one that I don't think has a name? The Talmud refers to it as Ta'anat HaMinin, with "minin" meaning "heretics", but it's the belief formulated by Irenaeus that only the Ten Commandments were given at Sinai, rather than the whole of the Torah, and it's the way that Christianity reconciled its rejection of the mitzvot with its keeping of the Tanach as scripture.
