Is there only one question I have: Is the repentance of one who mocked religion accepted?

Mocking religion is apostasy, even if done in jest, as Allah Almighty says: "If you ask them, they will surely say, 'We were only indulging in idle talk and play.' Say, 'Is it Allah and His verses and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief."

One who mocks religion must repent to Allah, utter the two testimonies of faith (Shahadatayn), and regret their action. For Allah forgives all sins for those who repent with sincere repentance, even polytheism, as Allah Almighty says: "Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" And Allah Almighty says: "Except for those who repent, believe, and do righteous deeds; for them Allah will change their evil deeds into good ones. And ever is Allah Forgiving and Merciful."