First, guys, I feel like we've played this soundtrack before.
That is one thing He chose. He can certainly choose to do other things, too.
Christ can absolutely reveal Himself to a muslim, even in the context of the Koran, and the muslim can listen to Him and follow Him while still being a muslim. (Particularly for certain groups of muslims for whom Christ is a real figure.)
"Christ" has many names. Some of them we may not even know.
This whole "If it isn't the way I think it is then Christianity is a lie" is a non-Biblical absolutist emotional appeal. That there may be a misunderstanding does not make something a lie.
What you're saying is the Bible cannot be trusted?