Want a warrior priest? Sure, just create a priest title and give it to the warrior. The priest class are just preachers anyways...
Want a religion without priest classed nobles? What? that is just stupid you need priests to have a religion. Only preachers can be priests!
Nice double standard...
Anaris' point stands. You are prefectly allowed to create a guild, name its members priests, and have a bunch of nobles debate religion without ever preaching to the peasants. This has been done before (the Chaos Requiem for example).
However the whole religious infrastructure of religion in BM is geared towards preaching to commoners and then using your influence on these commoners as a weapon. The rest is just RP. If you don't have priests, then the whole infrastructure falls apart... and your RP remains, which is perfectly fine.
