What is the Islamic ruling for a woman who intended to declare her Islam but might marry a Christian man due to family circumstances, and what will be her fate and the fate of her children in this world and the hereafter if this marriage takes place? And is she considered an apostate in this case?

What has been mentioned about the situation of this sister is saddening, and her marriage to a Christian is zina (fornication/adultery), caused by mistakes on her part: delaying the declaration of her Islam, accepting a proposal from a Christian and reciprocating, and informing the suitor about her father's secret.

We advise her to remain steadfast in Islam, to thank Allah for the blessing of guidance, and not to follow the footsteps of Satan, who seeks to lead her into indecency and evil, such as zina and injustice to her offspring. This marriage will cause her to lose her religion.

The door to salvation is open, and she must be resolute and sincere, declare her Islam publicly, annul the engagement, seek help from people of knowledge, and frequently recite the Qur'an and perform dhikr (remembrance of Allah).

The questioner should stand by her and help her declare her Islam.