If a Muslim woman marries a non Muslim man, does she become a disbeliever?
It is similar to fornication. In fact, it could be regarded as being worse than it. However, we do not render her as a disbeliever by that action.
Ash-Shaykh Bin Baaz, rahimahullah, was asked the following question:
Q 5: Some Muslim women marry non-Muslim men, what is the ruling on such marriages? Are the women considered to be Kafirs (non-Muslims)? Are the children born from this marriage acknowledged as legal progeny?
A: This marriage is Batil (null and void). If the couple were not aware of the invalidity of this marriage when contracting it, the children born from this marriage are attributed to the father; since they deemed the contract valid when contracting it. If they know the ruling on the marriage, they have committed fornication and the children born from this marriage will not be acknowledged as legitimate offspring.
A Side Note: These are from the matters which Shaykh Ubayd al-Jaabiree (may Allaah rectify his condition) was disparaged and criticized for, being the reason he uttered the following words when he was asked concerning a muslim woman who is married to a christian:
“How does a muslim woman marry a Christian?! This is disbelief and apostasy… if she is a muslim, relay to her the greetings [Assalaam] and to not remain in the bonds of this Christian for verily if she remained after this then she is a disbeliever and an apostate… ”
May Allaah guide us all to that which is correct.
AbdulFattaah Bin Uthman