I share the idea it should be dealt IC.
While he didn't clearly stated he refused the existence of all Gods, he did attack the legitimacy of the gods, brought in question their powers and acted in a very disrespectful manner about them. Like Sonya mentioned, i think it's fair to consider this as Blasphemy and if it was directed towards a main or well-seen religion within the realm, you can consider this as a serious offence and deal with it as a major crime against the realm, it's purely heresy. Since he's noble i guess he can have the chance to retract, even more if it's his first offence. And If "these" Gods were outsider Gods for the character, i guess he just got more enemies and it should be seen as very reckless (i have that vision of Achilles cutting the head of Apollo statue) But, even if it's still an enemy Gods targeted, people should see him as cursed or mad, he should at least be warned even in that case, this will bring no good to his realm if he angers the gods. If he persists i would ban him.
