It sounds like you don't like the way he makes decisions as his character, but it's his character, right? If he does stuff that's a slight against his god, don't punish him for it, use it as a plot device. Maybe he prompts some sort of divine vision where his god scolds him lovingly because while he sees the goodness of intention, it goes against his main tenant and he must kill the man or lose his connection to that God.

This then sends him on the quest for a new god... Idk I'm getting ahead of myself here, basically don't be a cock block if it's a decision someone is making for their character. It sounds like he was being the opposite of disruptive from what you're saying.