It’s very important to know that one of the well-established principles in Islam is: “There should be no compulsion in religion”. This is based on the Glorious Qur’an, in which Almighty Allah made it clear, in more than one verse, that no one should be forced to embrace Islam, for this religion respects people’s freedom of choice. Allah says: (Let there be no compulsion in religion: Truth stands out clear from Error: whoever rejects evil and believes in Allah hath grasped the most trustworthy hand-hold, that never breaks. And Allah heareth and knoweth all things.) (Al-Baqarah 2: 256)
Dr Muzammil Siddiqi, former President of the Islamic Society of North America, states: It is wrong to force someone to embrace Islam. Since he accepted a Christian wife, it is not right for him to threaten with divorce for example for his wife to convert. This is against the teachings of Islam. A husband can try however to explain to his wife the beautiful teachings of Islam and should try to convince his wife with his good example and behavior that it would be good for her to accept Islam, but he should not use marriage as a trick to bring her into Islam.
My advice to an interested wife in this situation is to ask her husband to suggest some good books to her about Islam or to take her to Islamic gatherings and Islamic centres. This will help her meet with other Muslims, study the Qur’an and have access to some other Islamic books. If she is convinced then she may accept Islam, otherwise she can remain a Christian and can still be a good wife for her Muslim husband.