Morton Lither, a former priest of The Cult of Azaaroth, decides to start a protestant branch of it after a disagreement over something relatively silly, like the color of the "tablecloth" they use to cover the alters during the virgins' sacrifices.
Zig Zagged: The Cult of Azaaroth seem to be scary cultists. But they have good intentions. But they achieve their good goals via torture and human sacrifice. But it turns out the "torture" is really Training from Hell, allowing the "sacrifice victims" to voluntarily Ascend to a Higher Plane of Existence. But when they get there, they're conscripted into a war of angels vs demons— and both sides claim to be the angels.
Averted: Evil deities have no worshippers at all, or else there are no devil deities in the universe.
Defied: An evil cult starts operating in an area, but the locals quickly take note and just as quickly extirpate it from the land.
Discussed: "You remember the rhyme - 'If cloaked all in red, just aim for the head'? The Darklight priests only wear red".
Conversed: "All those skulls on that temple had to come from somewhere; you'd think someone would have noticed and, you know, asked them to leave some for the rest of us".
The "evil cult" and the Most Popular Religion that fight them are actually two denominations of the same religion that worship the same god in different ways. Each side sees themselves striving for good and fighting evil...
The Cult of Azaaroth began as a brutal, vicious, bloodthirsty religion... but since Azaaroth is nowhere to be seen, the religion eventually goes mainstream and, to attract converts, slowly turns into a Lighter and Softer version of itself. Red wine substitutes for blood, unpleasant tenets are explained away as complex metaphors or swept under the rug, sacrifices are replaced by plays in which nobody actually gets hurt, and the few traditionalists who still bother with skulls at all use ceramic ones instead instead of the real deal...
...Which is what the true worshippers of Azaaroth, who have seen him, intended so that they can continue to worship sacrifice people while the Lighter and Softer religion acts as a front for there true activities.