Anyone still in here? Islam is unique in that it delegitimizes its foundation and heritage traditions - Judaism and Christianity - while at the same time using those same traditions to legitimize itself and claim superiority over the Abrahamic traditions. You can't have it both ways.
Just one example of the way this works is with the angel Gabriel. The angel Gabriel is the archangel who delivers news about Jesus' birth to Joseph and Mary as the story goes. Obviously, Christians believe that Gabriel had the correct message and that he was a valid and truthful messenger from God. Islam takes Gabriel and makes him the messenger of Allah to Mohammed in the cave. There is one problem with that. When Gabriel speaks to Joseph and Mary he says in no uncertain terms that Jesus is the Messiah. When Islam uses Gabriel this is not addressed when Gabriel would necessarily be contradicting himself and God's directive toward Jesus, Joseph and Mary in speaking to Mohammed.
If Muslims are to believe Gabriel in one instance, they must believe him in the other when the two messages are in direct contradiction to each other. Either that or Gabriel is not a reliable messenger and he isn't to be believed in either case.
Not the most elegant way of putting it, but I hope you see the point. Islam - at least use a different angel if you are going to contradict the entire development of the Abrahamic tradition, which is what you rest your own legitimacy on.