Serving the Deity

Never mock any deity

Do not ridicule or deride any of the devatās. Respect every form of the divine you meet.

The Nectar of Devotion lists deriding the demigods before the Deity among the offenses. Take it as a rule for the whole of life: whether in a temple, a film or a conversation, do not make fun of any god or goddess, or of the people who love them. Respect for what others hold sacred is part of bhakti.

Whose teaching
Vedic scripture
Where it is taught
The Nectar of Devotion, ch. 8: offense 32
Source
Vedabase