If the woman who wants to marry a Muslim man is one of the people of the Book (i.e. Jew or Christian), there is no Shar’ee impediment to this marriage, so long as it fulfils the Shar’ee conditions, such as the requirement that she chaste. But the Muslim husband should be keen to bring his wife into Islam so as to save her from eternity in the fire and so that he and his children will have a home that is based on Islam. But if the woman who wants to marry a Muslim man it is not one of the people of the Book, then it is not permissible for a Muslim to marry her.