How should I deal with my daughter who is befriending a Christian, knowing that she does not believe in religions, and that I am married to a woman who believes in nothing? And should I cut ties with her or expel her?

Allah has entrusted fathers with the responsibility of their children, burdening them with the duty of raising them upon the teachings of Islam. Neglecting this responsibility results in children disobeying their parents and failing to distinguish between a Muslim and a disbeliever. The father must repent for his negligence and separate his daughter from the Christian man if the situation is still under his control. Otherwise, he must denounce the act and clarify Allah's ruling. If denunciation proves ineffective, and boycotting the daughter leads to her being deterred from her action, then boycotting her becomes necessary. Otherwise, there is no benefit in boycotting. Finally, it is advised to emigrate from the disbelieving country if one cannot control those whom Allah has placed under his charge.