You're not going to get people to accept something that they may have no concept of in this age. Yes, religion still plays a major role in our lives. But in our modern age a lot of separation has occurred that makes us take mundane matters often more seriously than spiritual ones.
To give a more vivid illustration of our modern treatment of some religions, at some point in Ancient Greece their gods were feared, and people really did not mess with the priests in fear that they'd be...turned into some weird monsters or something.
Now? We made three games in which some Spartan guy kills Ares and in the latest one he boots Zeus out of Olympos.
Our current popular concept of Hell as fire and brimstone came from Dante's The Divine Comedy. By the way, remember that game about the Spartan guy? Yeah, they cloned the mechanics of that game, and replaced the Spartan guy with a Crusader guy who kills Death, gets his scythe, and messes up Hell, all while still being mortal or something.
So my point is, I have a pretty good feeling that there are very few modern humans living in all of the continents except Antarctica (And even there, I'm pretty sure the scientists aren't waking up every morning in their monasteries) who really think of religion as anything significant in the BM world, apart from maybe an interesting little flavor. New players certainly would NOT understand that it can be a means for power. No, seriously, they will not understand that, unless you are very clear how that works, which so far, it is not clear.
Besides, this is still a game, and even if we are being seriously Medieval about it (Hey, why haven't I seen people roleplay their nobles as dying due to the various diseases that permeated in utterly filthy Medieval Europe? Come on, man up and be serious: Kill off your characters. lol), there are still some concessions to keep this enjoyable as a game. For one thing, make this mechanic of religion something more applicable with effects that can be seen immediately. Then again, religion is often best served subtly.
So what? Realism doesn't always lead to enjoyment. Would you like to be really seriously Medieval? How come I don't see the elder priests leading regular religious gatherings? Surely not ALL religions on Dwilight have no concept of having their members meet at least somewhat regularly in one of their temples to gain blessings of some sort? (In other words, none of those regular gatherings that just about all major real world religions have, and which would have been a bit more important to make back in the Middle Ages probably). You know why? Y'all are too lazy to do something as dedicated as that.
Make religion more serious? You can't teach a cat to bark you know.