"Gods do tend to choose those suited to them, usually. I think in this case you would be relying a lot on the god to know whether you were suitable; you do not really know enough about any of these gods, even Asmodeus, to make that decision for yourself. It is possible to stop being a cleric if you decide you don't want to be one. I agree that this is unlikely to work, especially given the barrier about you, but there is not any harm in trying so long as you avoid calling out to, say, Rovagug."