We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
You are using an out of date browser. It may not display this or other websites correctly. You should upgrade or use an alternative browser.
This goes for all Orthodox heresies except Bogomilists and Iconoclasts. Pretty much justified since the rest of those heresies are ancient and well established.
For heresies that did not traditionally have religious heads it might make sense to simply have autocephalous religious heads in each heretical kingdom if enough of the kingdom has become heretical. It is indeed possible to have such a system modded in with no religious head title and no pentarchs.