All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
Allaah has made it lawful for Muslim men to get married to chaste Muslim women and to chaste women from the people of the Book; He Says (what means): {This day [all] good foods have been made lawful, and the food of those who were given the Scripture is lawful for you and your food is lawful for them. And [lawful in marriage are] chaste women from among the believers and chaste women from among those who were given the Scripture before you, when you have given them their due compensation, desiring chastity, not unlawful sexual intercourse or taking [secret] lovers. And whoever denies the faith – his work has become worthless, and he, in the Hereafter, will be among the losers.}[Quran 5:5]
It is forbidden for Muslims to get married to polytheists or pagan women; Allaah Says (what means): {And do not marry polytheistic women until they believe. And a believing slave woman is better than a polytheist, even though she might please you.}[Quran 2:24]
If she is following one of the religions of the People of the Book and refuses to enter Islam during the marriage act, your marriage to her is nonetheless legal and correct according to the Sharee'ah.
Allaah Knows best.