Celebrating a holiday and taking part in festivities does NOT make one an idol worshiper.
He likely would make fun of "shariah," injunctions because these in question are derived from impotent (i.e powerless), pseudo-fascists who spin their wheels and try to pepper their distaste for him with religious rationalizations.
Only Allah knows one's intention, so please don't pretend that you do.
u r rite that allah knows the real intention. but ur actions determine ur status and standing as a muslim in this world.
if this is not the case then there wud have no need to differentaite between muslim and momin and muslim and fasiq.