Islam declares all people are originally born Muslims, but their belief was corrupted by their upbringing, and they became corrupted, hence deviated from the true religion of Islam. Therefore, when someone accepts Islam, he/she is called a “revert’ and not a “convert”, meaning reverting to his/her original belief. For a Christians who are ignorant, Muslims are taught to tell Christians that Islam has the same root as Christianity in that both religions come from Abraham, both held Jesus in high reverence, his virgin birth and there is a whole chapter in the Quran on Mariyam (Mary). Furthermore, the bible of the Christians was corrupted, and Islam came into existence through the revelation of God (Allah) the final divine message to Muhammad, bringing the final truth superseding all previous revelation from the prophets including Jesus.
Christians must be discerning and not be deceived by superficial similarities often expounded by Muslims. First, read your bible carefully and understand the core doctrines especially of the concept of our God, the person of Christ and his works, the redemption of God and the gift of salvation by grace. Conversion means the rejection of sacrificial atonement of Christ and hence your salvation. If your conversion is because of marrying a Muslim, then the loss of salvation is also applicable to your children as they are mandated to be Muslims under Islamic law. So, think cautiously of the grave consequences.
Provided below is a video which discusses the key questions you need to know about Islam. These are what the Quran states and contradict the biblical truth. The video is presented by an ex-Muslim, who is an atheist, so he presents the facts objectively and not biased towards Christianity. In essence, from the Christian perspective, Islam presents another gospel of Jesus that is antichrist as defined in 1John1:22,4:3. The question every Christian must ask is “How much do I love Jesus Christ?”
Acts 4:12 "Nor is there salvation in any other, for there is no other name under heaven given among men by which we must be saved.”