Bart Ehrman has been popular in Muslim circles as a reliable and authentic source for understanding Christianity. A typical quote from Bart used by Muslims is the following:

The argument based on Jesus as liar, lunatic, or Lord was predicated on the assumption that Jesus had called himself God. … I had come to realize that none of our earliest traditions indicates that Jesus said any such thing about himself. And surely if Jesus had really spent his days in Galilee and then Jerusalem calling himself God, all our sources would be eager to report it. To put it differently, if Jesus claimed he was divine, it seemed very strange indeed that Matthew, Mark, and Luke all failed to say anything about it. Did they just forget to mention that part? I had come to realise that Jesus’ divinity was part of John’s theology, not part of Jesus’ own teaching. (Bart Ehrman, Jesus Interrupted, 2009, pp. 141-142)

But now Bart has changed his mind.

Until a year ago I would have said – and frequently did say, in the classroom, in public lectures, and in my writings – that Jesus is portrayed as God in the Gospel of John but not, definitely not, in the other Gospels of Matthew, Mark, and Luke. … I finally yielded. These Gospels do indeed think of Jesus as divine. Being made the very Son of God who can heal, cast out demons, raise the dead, pronounce divine forgiveness, receive worship together suggests that even for these Gospels Jesus was a divine being, not merely a human. … So yes, now I agree that Jesus is portrayed as a divine being, a God-man, in all the Gospels. But in very different ways, depending on which Gospel you read. (Bart Ehrman, ehrmanblog.org, posted 13-04-2014)

This is an enormous change in understanding and Bart is to be commended for his honesty, however, Muslims need to consider the changing nature of his arguments when they quote him as a reliable and authentic source for understanding Christianity.