Does a mother's anger or disobedience constitute a major sin if she refuses her son's marriage to a righteous Christian woman who is open to guidance, and what are the conditions for a valid marriage in this case?

It is permissible for a Muslim man to marry a chaste woman from among the People of the Book, but it is preferable and better to marry a Muslim woman of good character. If the mother forbids her son from marrying a woman from the People of the Book, he must obey her, for honoring one's mother is among the greatest obligations, and disobeying her is a major sin. A Muslim should seek a Muslim woman of good character and piety and sever his relationship with the woman from the People of the Book. If he hopes for her conversion to Islam, she can be invited to Islam through righteous Muslim women or Islamic centers. It is also necessary to strive to reside in Muslim countries to avoid the dangers of non-Muslim lands to one's religion and morals.