I want to share with you what I believe are the best arguments to prove that Jesus is God. It works with Jehovah Witnesses, Mormons, Islam, and any other ism that teaches that Jesus was not God manifest in the flesh.
Islam teaches the Jesus was just a man, a prophet, but just a man. It teaches that Christians have committed the greatest sin and blasphemy of all, shirk. This is making a man equal to God. Making a man equal with God would be blasphemy for Christians also. We do not teach that a man became God, we teach that God became a man. The eternal Word, Jesus, the Son of God, became flesh and dwelt among us.