What is the ruling on a Muslim man marrying a married Christian woman who wishes to convert to Islam, knowing that her family might kill her if she converts, and the young man's family rejects his marriage to a non-Muslim woman?

As long as a woman is married, it is not permissible to marry her, according to the Almighty’s saying: "And [prohibited to you are all] married women." If she embraces Islam and her husband remains a disbeliever until her 'iddah (waiting period) expires, then it is permissible for her to marry. If the young man wishes to marry her after her conversion to Islam, the expiry of her 'iddah, and her husband's non-conversion to Islam, he must inform his parents and try to convince them. If they refuse, he must obey them unless he fears harm. The young man must be careful not to fall into haram (forbidden acts) with her before marriage. It is advisable to care for the woman and encourage her to learn about Islam, clarifying the falsehood of Christianity and that Islam is the true religion. If she embraces Islam, there is no harm in her concealing her faith until it becomes stable, but she must perform the rituals of the religion, even if secretly.