What is the religious ruling regarding a married man with children who frequently says, "Damn your religion," and "Even if God Himself came down from heaven, I wouldn't do this," and then regrets it and swears not to repeat it? What is the expiation for this sin, and how can he break this habit?

The aforementioned statements are infidel (Kufr) and expel their utterer from the faith due to their mockery of religion and its sanctities. This is based on Allah's saying: "Say, 'Is it Allah and His verses and His Messenger that you were mocking?' Make no excuse; you have disbelieved after your belief." And the Prophet (peace be upon him) said: "Indeed, a man may utter a word that incurs the wrath of Allah, and he would not imagine it to reach what it has reached, but Allah records for him His wrath until the Day he meets Him." Whoever utters such words must repent sincerely, seek much forgiveness, and perform righteous deeds. The fear of Allah and His constant awareness protect the servant from error and lead to Allah's pleasure and His Paradise.