Whilst it is true that Jesus wsn't the King of the Jews, he was supposedly sent to Earth by God to continue and further His work and Word to the humans. The Jewish faith, however, refuses to acknowledge Jesus as the son of God and are still awaiting God's first coming and as such do not accept the New Testament or its teachings. Christianity was started by the disciples and spread across the globe and DOES acknowledge Jesus as the Son of God, and that His coming to Earth, teachings and subsequent execution and resurresction all formed a new extension to the scriptures and therefore, the New Testament.