Praise be to Allah.
If a Muslim wants to marry a Christian woman, she does not have to become Muslim first, because of the general statement in the Qur’aan (interpretation of the meaning):
“Made lawful to you this day are . . . chaste women from those who were given the Scripture (Jews and Christians) before your time . . .” [al-Maa’idah 5:5].
The conditions for a non-Muslim woman to marry a Muslim man are that she should be of the People of the Book (Jewish or Christian) and that she should be chaste.
We remind the Muslims living outside the Muslim world that they should not rush into taking such a step, and if they wish to do so, they should think long and hard, even though marrying a woman of the People of the Book is permitted in principle. There is a very real possibility of the children becoming Christian, especially in countries where the law favours the non-Muslim mother. In fact many such tragedies have occurred. We ask Allaah to guide us all and give us strength. May Allaah bless our Prophet Muhammad.