What is the ruling on filial impiety towards parents who did not raise their children in the religion, who command them to disobey God, and who refuse their daughter's marriage to a righteous man, with the father also being accused of insulting religion and the Quran?

Insulting religion, or God, or the Qur'an, or the Prophet, peace be upon him, is an act of disbelief (kufr) and apostasy from the religion. Anger is not an excuse unless it is so intense that the person does not realize what they are saying. Your father must repent of this disbelief; otherwise, his prayers and fasting will not benefit him.

As for your relationship with your parents, you must treat them with kindness and dutifulness, and invite them to guidance with patience and wisdom, and continue your good companionship with them. We do not recommend moving away from them for university studies as a solution, as that may lead to greater harms.