There were a few religious communes during Medieval times that had Anarchosynicalist tendencies - most notably the Taborites, the English Ranters, the Adamites and Brethren of the Free Spirit.
They tended to religious reformers who formed communes, were anti-establishment, got accused of immoral behaviour resulting in them being declared heretics and thus getting stomped out by the establsihed Church.
So yes quite possible, especially if your world is Polytheist and thus lacking a tradition of anti-heretical Crusades.
Monarchs are too busy doing politics to concern themselves with a few rural communes with weird ideas (at least until they start murdering virgins and summoning demons)