The only ways to ever remove a religion are The Purge of the Unfaithful ritual (which requires a state religion) or the Inquisition spell. The Grigori get The Luonnator druid-UU at strength of will (They have a level requirement, while druids do not; this seems wrong), but the Illians have no way to remove a religion once it spreads. Hopefully this will be addressed before
Ice.
The Agnostic Trait does slow the spread of religions.
When I play as the Grigori (and not my modmod) I try to spread religions to my cities as much as possible. Grigori Medics who randomly get religions from the cities where they are built are the equivalents of High Priests.
In my version, Luonnator are available at Philosophy. (I'm rearranging the tech tree slightly, so that Priesthood, Way of the Wicked, and Way of the Wise come right after Mysticism, and Philosophy requires either Way of the Wise or Way of the Wicked. Philosophy is also more expensive, and is the tech prereq for Rebublic. Still, this is sooner that Strength of Will.) They are weaker, but lack the level requirement. They will attack disciple units even it stacks of stronger units, except in cities, like the Khmer War Elephant UU targets mounted units in BtS. They don't have the Inquisitor promotion/spell, but have a unit-specific "Enlighten" spell. This works like Inquisition minus the state religion requirement,
so you can use it to rid a rival's cities of his State Religion. I'm still trying to decide whether I should let them move through rival territory, since otherwise rivals (at least human ones) would refuse to give you open borders. If so, I'll probably have to make the spell take longer or often fail. I'm also thinking I may make Enlighten also remove the religion from units in the casters stack (probably a small, random chance to do so for each unit). Because of the Grigori Medic exploit, I made Priest spells require state religion while priests themselves don't, an moved the Cure Disease and Heal spells come from their medic promotions (Grigori medics don;t have divine or channeling anymore). That also means that a Priest (or Esus recon unit) who listens to the Luonnatar and abandons his god
will lose all its spells.
Hows
that for Militant Agnosticism for ya?
(Plus, my adventurers can join a city as a Local Legend, (giving free xp, culture, and Adventurer GPP) and upgraded Adventurers can revert back to an adventurer unit at any time, ad upgrade to a unit of a very different type. The Grigori are really Awesome in my version, but to be fair I'm making religions much stronger too)
I also gave the Illians some "White Hand" disciple UUs (unitcombat_disciple lets them purchase the inquisitor promotion), and gave Inquisitor to the Auric Unit. My version of Auric is basically a weak Mage with Ice affinity, plus Ice 1 (I've implemented the Ice sphere), command 1-2 and inquisitor. He can be built, and is a starting unit in non advanced start games (like Lucian). Like Basium/Hyborem(/Orthus), his death costs you your traits.
