Punishment for Marrying a Non-Muslim Man
Question

How is a woman to be punished if she marries a Christian? How often is it carried out and in what countries is it most common?
Praise be to Allah.Can a Muslim woman marry a non-Muslim man?
It is not permissible for a Muslim woman to marry a non-Muslim , whether he is Jewish, Christian or an idol-worshipper. This is because the man has authority over his wife, and it is not permissible for a non-Muslim to have authority over a Muslim woman. For Islam is the true religion and all other religions are false. Allah says (interpretation of the meaning):
“And give not (your daughters) in marriage to Al-Mushrikun till they believe (in Allah Alone).” [al-Baqarah 2:221]
“And never will Allah grant to the disbelievers a way (to triumph) over the believers.” [al-Nisa 4:141]
 And the Prophet (peace and blessings of Allaah be upon him) said: “Islam should prevail and should not be prevailed over.”
Punishment for marrying a non-Muslim man
If a Muslim woman marries a non-Muslim when she knows the ruling, then she is an adulteress, and her punishment is the punishment for adultery. 
If she was ignorant of the ruling, then she is excused but they must be separated, and there is no need for a divorce because the marriage is null and void. 
On this basis, the Muslim woman whom Allah has honoured with Islam and her guardian must beware of that and must adhere to the limits set by Allah, and they must feel proud of Islam. Allah says (interpretation of the meaning):
“Those who take disbelievers for Awliya (protectors or helpers or intimate friends) instead of believers, do they seek honour, power and glory with them? Verily, then to Allah belongs all honour, power and glory,” [al-Nisa 4:139]
For more, please see these answers: 230057 , 1825 , 20884 and 1917
And Allah knows best.