Ya ukhatees wa akhees, do you know that if you make fun of those who are religiously-committed, insulting them and mocking them, you are in a serious danger, and that these actions may put you beyond the pale of Islam? Eiitaquulallah-fear Allah (swt)

Shaykh Ibn ‘Uthaymeen (may Allaah have mercy on him) was asked about the ruling on making fun of those who adhere to the commandments of Allaah and His Messenger (peace and blessings of Allaah be upon him)?
He replied: Making fun of those who adhere to the commandments of Allaah and His Messenger (peace and blessings of Allaah be upon him) because of their commitment is haraam and is very dangerous and serious, because there is the fear that his hatred for them may be based on hatred of what they are adhering to, namely the religion of Allaah. In that case mocking them is mocking the path that they are following. They are like those of whom Allaah says (interpretation of the meaning):
“If you ask them (about this), they declare: ‘We were only talking idly and joking.’ Say: ‘Was it at Allaah, and His Ayaat (proofs, evidences, verses, lessons, signs, revelations, etc.) and His Messenger that you were mocking?â€Â
Make no excuse; you disbelieved after you had believed’â€Â
[al-Tawbah 9:65-66]
These words were revealed concerning some of the hypocrites who said: “We have never seen anything like these reciters – meaning the Messenger of Allaah (peace and blessings of Allaah be upon him) and his companions – they are the most greedy, the most false of speech and the most cowardly in battle.†Then Allaah revealed this verse concerning them.
Those who make fun of the followers of truth because they are religiously-committed should beware, for Allaah says (interpretation of the meaning):
“Verily, (during the worldly life) those who committed crimes used to laugh at those who believed.
30. And, whenever they passed by them, used to wink one to another (in mockery).
31. And when they returned to their own people, they would return jesting;
32. And when they saw them, they said: ‘Verily, these have indeed gone astray!’
33. But they (disbelievers, sinners) had not been sent as watchers over them (the believers).
34. But this Day (the Day of Resurrection) those who believe will laugh at the disbelievers
35. On (high) thrones, looking (at all things).
36. Are not the disbelievers paid (fully) for what they used to do?â€Â
[al-Mutaffifeen 83:29-36]
Majmoo’ Fataawa al-Shaykh Ibn ‘Uthaymeen, 2/question no. 236.
Insulting a Muslim is a major sin, especially if one insults him for being religiously committed and righteous. There is the fear that the one who does this may fall into apostasy as stated above with regard to mocking them.
It was narrated from ‘Abd-Allaah ibn Mas’ood (may Allaah be pleased with him) that the Prophet (peace and blessings of Allaah be upon him) said: “Insulting a Muslim is immorality and killing him is kufr.â€Â
Narrated by al-Bukhaari, 48; Muslim, 64.