What is the ruling on a father marrying off his eldest daughter to someone religiously unsuitable, and allowing his younger daughter to go to a Christian monastery with her friends without her mother's knowledge, in addition to her living with her paternal grandmother because of her refusal to live with her mother?

We advise making an effort to save your daughter from deviance by following these steps: Communicate with her with maternal affection and make her feel your concern for her, remind her of Allah, His blessings, and the severity of His punishment, seek help from Allah and from people of knowledge and goodness to clarify the danger of shirk (polytheism) and associating with bad company, seek assistance from influential relatives to pull her out of her current situation, repent to Allah and seek His forgiveness, and frequently supplicate for her during times when prayers are answered.