Unfortunately for most of them (Muslims, that is), it will be their deaths for them to realize that they ARE following a lie. They will not believe it until they see proof and that proof will rear its head when they die. Then they will know, without any doubt, that Jesus is Lord, Muhammad that they hold so dear is a fake and Allah really is Satam who is laughing at them probably saying "Thou Fool, you should have listened to the Christians but I tricked you to follow me!"
Just another one of those "I told you so but you did not listen" moments.