It is quite sad to think all the followers of these religions believe in God/Allah. Yet they disagree with each other.
Jesus (upon him peace) was called king of the Jews(Mathew 23.38), Why? If was living differently then he would've called something else. He was living like a Jew, so this confirms what came before. It was Paul who changed Christianity to what it is today, after the forcing of the trinity onto the people by the roman emperor Constantine.
Jesus (upon him peace) spoke in Aramaic and he "Peace be onto you." Mathew 24.36. Peace means salam in Arabic and to you means alikum. So what was he saying? Salam alikum, the Muslim greeting the same greeting that Adam (upon him peace) gave then angels.
The source is the same but people have changed the direction, its time to put this back together.