And when the angels said: O Mary! Allah gives you the glad tidings of a command from Him: his name shall be Messiah, Jesus, the son of Mary. He shall be highly honored in this world and in the Next, and shall be one of those near stationed to Allah.Now the Koran never says that Jesus is the Son of God, but has Jesus even denying that.
Mohammed (600+ A.D.) borrowed what was already taught to Christians. Then he paid lip service to, and modified, those beliefs he chose to help bring in some on-the-margins mostly ignorant Arabs who had heard of those Christian ideas.
He used the word Messiah as a name to the ignorant, and absent its meaning.