Answer
Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- Islam does not encourage the interfaith marriages.
2- The general rule of Islam is that Muslims should marry Muslims.
3- A Muslim male or female should not marry a non-Muslim male or female.
4- The only exception is given to Muslim men who are allowed to marry the chaste girls from among the People of the Book.
A Muslim woman is better suited to a Muslim man than a woman of Christian or Jewish faith, regardless of her merits. This is because marriage is not based on fulfilling one’s sexual desires; rather, it is an institution. It aims to establish a home on the basis of tranquility, faith and Islamic morals. To fulfill this task, the whole family must apply Allah’s course and try to convey His message.
It is obvious that Islam made it impermissible for a Muslim woman to marry a non-Muslim with aim of keeping her away from things that may jeopardize her faith.
In fact, Islam aims at protecting religion. To achieve this goal, it prohibits a Muslim from being involved in something that represents a threat to his religion. A Muslim woman will not feel that her religion is secure while being with a Jewish or a Christian husband especially as the majority of the People of the Book do not show due respect to our Prophet, Muhammad (peace and blessings be upon him).
Allah Almighty says: “And the Jews will not be pleased with thee, nor will the Christians, till thou follow their creed. Say: Lo! The guidance of Allah (Himself) is Guidance. And if you should follow their desires after the knowledge which hath come unto thee, then wouldst thou have from Allah no protecting friend nor helper.” (Al-Baqarah 2:120)
Given the fact that the husband is generally the head of the household, it’s not far-fetched for a non-Muslim husband to prevent his Muslim wife from performing some Islamic rituals which may seem a nuisance to him, for example fasting, or even refraining from marital relations during the fast.
As a result, he might force her to change her religion, and if she refuses, the situation may culminate in divorce.
As for why Islam allows a Muslim man to marry a Christian or Jewish woman, it’s clear that every Muslim believes in Moses and Jesus (peace be upon them) and he holds all the Prophets of Allah in high esteem. Thus a Muslim finds no harm in his wife’s being a Christian or a Jew, for the spirit of tolerance Islam holds for other religions is ingrained in him.
Allah Almighty knows best.