All major groups of Muslims have forbidden Muslim women from marrying non-Muslim men.
According to some, this prohibition serves to preserve the Islamic faith from dilution and expand it, within societies which are patriarchal but multi-faith.
There are restrictions to whom a Muslim man can marry.
Muslim men are forbidden from marrying polytheist women.
A polytheist woman would have to convert to Islam if she would want to get married to a Muslim man, according to Islamic principles.
(See verse below) Muslim women are forbidden from marrying non-Muslim men according to Islamic law.
This systemic method of expanding the Muslim community in any multi-religious society is assisted by the ability for Muslim men to marry more than one non-Muslim wife (a possibility usually not available to non-Muslim men) and therefore secure all of their offspring for the Islamic faith - provided that the society acknowledges a patrilineal religious system in which only the father's religion is passed down.
Under Islamic law, if a non-Muslim woman is married to a non-Muslim, and she converts to Islam, the marriage is suspended until her husband converts to Islam.She could, in theory, leave the non-Muslim husband and marry a Muslim one.Islamic Law has different regulations on interfaith marriage, depending on which of the two spouses is Muslim.It permits a Muslim man to marry up to four non-Muslim women from the People of the Book (that is, Christians and Jews) however some say this practice is no longer valid.In addition to this it is seen as "makrooh" (disliked) by Muslim scholars for Muslim men to marry outside the religion because the rightly guided Caliph, Umar, banned interfaith marriages for Muslim men.Islamic marriage rules between Muslim men and non-Muslim women are regulated by Islamic principles.