What is the ruling of Islamic law regarding a father who is subjected to psychological and physical pressures and imprisonment for refusing to disclose the whereabouts of his minor son, and is it permissible for him to hand over his six-year-old son to his foreign, polytheist ex-wife, given the impossibility of seeing him in the future?

Islam is a condition for custody, and a disobedient Muslim woman forfeits her right to custody. The father has a greater right to custody if one of the parents travels. What the father did to protect his son from shirk (polytheism) is commendable. Marriage to a woman of the People of the Book is permissible, but it carries great risks, and the story of the aforementioned husband is an example of this.