Reforming religions isn't really supported by the mod, a warning to that effect will be added to the next update

You might be a bit too hard on your own mod here, Karde. Creating or modifying vampire religions has worked reasonably well in my playthroughs.
I did experience some issues when I tried creating a new Shadow Inquisition faith. Once converted my character lost access to all Shadow Inquisition abilities. Maybe it is just a hunter problem.

@Karde, in \common\religion\doctrines\00_POD_special_doctrines.txt, should be

divinitatis_heresy_hostility = {
group = "special"
is_available_on_create = {
has_doctrine = special_doctrine_blood_divinity
}

special_doctrine_blood_divinity = {
parameters = {
hostility_override_bloodgnosticism_hostility_doctrine = 1
hostility_override_special_doctrine_blood_divinity = 1
}
}
}

It's now availaible on create for all faiths, that's why it adds it everywhere, not just hunters.