The Qur'an affirms that Jesus is the Messiah but denies that he is God, Yahweh. Part of the criteria for who the Messiah will be is that he is God (Isaiah 7,Isaiah 9,Jeremiah 23,Micah 5,Psalm 2,Psalm 110,Daniel 7,Proverbs 30,Psalm 45,Zechariah 2,Isaiah 48). So, either the Qur'an affirms the deity of Christ as the Messiah and contradicts its own claim about Jesus not being God which shows the Qur'an is false, or the author of the Qur'an is unaware that the Messiah is God and the Qur'an is false. Either way, the Qur'an is false, therefore Islam is false