Forbidden Magic, Fantasy Religions, and other Thoughts

[Arith Winterfell]

I've been working on designing a fantasy setting, but I've been struggling for ideas and narrowing down ideas from a general vague pool of ideas I have.

I've also been reading over Mailanka's Communion building ideas for inspiration and thoughts. The article: Here

Now, I mention IRL religious stuff here not to focus on it, but rather to explain my starting point and thus explain what "creative influences" shape my setting design. I'm an atheist IRL, so my point of view tends me toward a great distaste for religious zealotry and extremism. I admit, I tend toward religions in my setting that tend toward being good at first glance, but whose insistence on dogma and tendency toward Us vs. Them mentality ultimately mark them as being constrictive and tending toward a "Us/Righteous vs. Them/Wrong/Sinful."

That said, I'm mostly concerned with the inter-relationship between the Fantasy setting's religion and "Arcane" wizard magic. I've already established that there is an Arcane College in the setting which has political power and protects wizards and their usefulness in the setting.

I don't want to have an absolute antagonism between the Arcane College and those religions however either. That's too black and white a division. That said, I wanted to figure out a good way to use the default magic system to explore ideas of magic that religions forbid, but aren't directly crippling to player characters.

At the same time, I'm fascinated by the idea of "Forbidden Knowledge" in the vein of Lovecraftian Horror and would like to capture some element of that. At the same time I don't want to create a situation that disincentivizes actually learning and using Forbidden Knowledge/Magic.

So I'm just looking for general feedback and ideas on how to approach these elements in my setting from a design point of view?