Qur’an allows, but…
By Javed Ahmad
Islam allows Muslim men to marry women from the "People of the Book". And it is commonly assumed that the People of the Book are the present day Jews and Christians. Which is actually an error.
By "People of the Book", the Qur'an is actually referring to the Unitarian Jews and Christians, the followers of Prophet Moses and Prophet Isa. But today, we have different denominations of Judaism and Christianity. There is a group of Jews that follow the Torah, and then there are Jews that follows the Talmud (the Zionists). Again, there are some Christians that believe in One God and accept Jesus Christ as a Prophet (Jehovah's witnesses for instance), while there are others those who believe in Trinity (Catholics). And they are not all the same.
Muslim men are allowed to take as wives from among the Unitarian Christians, but not from the Trinitarians. Unitarian Christians are closer in belief with the Muslims in matter of theology; where as, the Trinitarians are quite opposite. And there are explicit warnings in the Qur'an regarding the belief in Trinity.
"They do blaspheme who say: God is one of three in a Trinity: for there is no god except One God. If they desist not from their word (of blasphemy), verily a grievous penalty will befall the blasphemers among them." (The Holy Qur'an, chapter 5, verse 76).
So what makes you think marrying a Catholic Christian would be valid? They are no different from the idol (a dead man hanging on a cross) worshippers!