Religion is a big deal in Chronicles of Elyria and they have already mentioned the possibility of being a part of those religions. We are certainly still waiting for more information about the mechanics of it all but I am very confident that religio, and religious orders, are going to play a considerable role in the worlds story.
Edit: A couple of sources for religious roles:
The Virtori are paladins and clerics.
Source: Caspian in IRC
Yes, you can become a priest of a religion, as we’ve talked about it in a previous Q&A there are at least four religions, and many of them do have priests. As to whether or not you can do ceremonies, you can. Whether or not they’ll have any effect or not, I guess you’ll have to wait and see.