Is disapproval by the heart sufficient for mocking religion, whether one is able to disapprove or not, even if that is when witnessing an abomination on television?

Denouncing evil in one's heart is not sufficient if a person is capable of a higher degree of denunciation. Mocking religion is one of the most heinous evils that must be denounced verbally or by action, as much as possible. While denouncing evil in one's heart prevents apostasy, it does not remove the sin if a person is capable of a higher form of denunciation.