A recent dialog with a Muslim on the Internet led to the Muslim claiming that Jesus was just "a Christ." He wanted to argue that Mohamed is also a Christ.
[3:45] The angels said, "O Mary, GOD gives you good news: a Word from Him whose name is `The Messiah, Jesus the son of Mary. He will be prominent in this life and in the Hereafter, and one of those closest to Me.' (cf. here)
[4:157] And for claiming that they killed the Messiah, Jesus, son of Mary, the messenger of GOD. In fact, they never killed him, they never crucified him - they were made to think that they did. All factions who are disputing in this matter are full of doubt concerning this issue. They possess no knowledge; they only conjecture. For certain, they never killed him. (cf. here)
[4:171] O people of the scripture, do not transgress the limits of your religion, and do not say about GOD except the truth. The Messiah, Jesus, the son of Mary, was a messenger of GOD, and His word that He had sent to Mary, and a revelation from Him. Therefore, you shall believe in GOD and His messengers. You shall not say, "Trinity." You shall refrain from this for your own good. GOD is only one god. Be He glorified; He is much too glorious to have a son. To Him belongs everything in the heavens and everything on earth. GOD suffices as Lord and Master. (cf. here)
[4:172] The Messiah would never disdain from being a servant of GOD, nor would the closest angels. Those who disdain from worshipping Him, and are too arrogant to submit, He will summon them all before Him. (cf. here)
Those of us who are Christians confess with Simon Peter:
Mathew 16:16 And Simon Peter answered and said, "Thou art the Christ, the Son of the living God."
Jesus Christ approved of this confession of faith, thus:
And Jesus answered and said unto him, "Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven. And I say also unto thee, That thou art Peter, and upon this rock I will build my church; and the gates of hell shall not prevail against it. And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.
But even after Jesus approved of this, because it was such a significant title, he instructed his disciples to keep that fact hidden:
Matthew 16:20 Then charged he his disciples that they should tell no man that he was Jesus the Christ.
But it did leak out, and eventually Jesus was called before the Jewish authorities to answer for this claim:
Matthew 26:63 But Jesus held his peace. And the high priest answered and said unto him, I adjure thee by the living God, that thou tell us whether thou be the Christ, the Son of God.
Jesus accepted this again:
Matthew 26:64 Jesus saith unto him, Thou hast said: nevertheless I say unto you, Hereafter shall ye see the Son of man sitting on the right hand of power, and coming in the clouds of heaven.
And consequently, the unbelieving Jews charged Jesus with blasphemy, failing to recognize that Jesus was really Christ and the Son of God, as he claimed:
Then the high priest rent his clothes, saying, He hath spoken blasphemy; what further need have we of witnesses? behold, now ye have heard his blasphemy. What think ye?
They answered and said, He is guilty of death.
Then did they spit in his face, and buffeted him; and others smote him with the palms of their hands, saying, Prophesy unto us, thou Christ, Who is he that smote thee?
The Koran refers to Jesus as the Masih which is a cognate to the Hebrew word that we express as "Messiah," for which "Christ" is the translation. The Koran even recognizes that Jesus is not simply "a Christ" but "the Christ." But the Koran does not understand that this title of "the Christ" is something that belongs to the Son of God - that there is a connection between the Christ and being the very Son of God.
May those who read the Koran and see this expression "the Messiah" look back to the Bible which came before and see what it meant for Jesus to be the Christ, and when you see what it says, turn from following Mohamed to following Jesus - put your trust in the Messiah of God.