Muslim men can marry the woman from the People of the Book (i.e. the Jews and Christians). Muslim men cannot marry polytheistic women unless she converts.

Can a Catholic marry a Muslim?

In an official church document released Friday, the Vatican discouraged marriage between Catholics and Muslims, especially Catholic women and Muslim men.

Is it a sin to convert to Muslim?

Islamic law prohibits forced conversion, following the Quranic principle that there is no compulsion in religion (Quran 2:256). However, episodes of forced conversions have occurred in the history of Islam.