Can a Muslim girl marry a non-Muslim (Christian)?
In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
The Shari’ah has never allowed Muslim girls to marry a non- muslim boy, no matter whether he is a Christian or a Jew or a Hindu etc. However, the Shari’ah has allowed a Muslim boy to marry a Christian or a Jewish girl. But there are two important points which should always be kept in mind in this respect:
- It is only the Christian and Jewish women that are allowed to be married by a Muslim. No woman of any other religion or belief is halal for a Muslim. The women who are Christian or Jew only by their names, and do not actually believe in any religion, like a large number of people in the Western countries, cannot be termed as “Ahl-al-Kitab” (People of the Book). They are atheists and it is not allowed in Shairah to marry an atheistic woman.
2. Shariah has allowed the Muslims to marry a Christian or a Jewish girl only where there is no apprehension that the husband or his children may come under her influence in religious matters. In the early days of the Islamic history every Muslim was duly equipped with adequate knowledge of his religion and had an unshaken commitment to the Islamic principles. Therefore, there was no apprehension that he would be misled by any foreign influence. Rather, he was supposed to convince his wife in religious issues. Therefore, if a Muslim is fully confident that his marriage with a Christian or a Jewish girl will never affect the religious life of himself or of his children, then there is no bar against such a marriage. But if he is not so confident, then, he must avoid marrying a non-Muslim girl. Even in the days of the Sahabah (the companions of the Holy Prophet (ﷺ.) some people were not advised to marry a Christian or the Jewish girl for this very reason. (See 158:2/4, Musanif Ibn Abi Shaibah) 
And Allah Ta’āla Knows Best
Mufti Arshad Ali
Darul Iftaa, Jaamia Madinatul Uloom (Trinidad)
 Contemporary Fatawa Mufti Muhammad Taqi
This answer was collected from Fatwa-tt.com, which is operated by the Darul Iftaa of Jaamia Madinatul Uloom (Trinidad and Tobago) under the advice and guidance of Mufti Ebrahim Desai (Daamat Barakaatuhum) of South Africa.