Jesus did many things but His purpose for coming was to die on the cross, to be the perfect sacrifice, without blemish, and purchase our place in heaven. So it isn't blasphemy, it is recognizing God's plan.
"Christ, the son of Mary, was no more than a messenger; many were the messengers that passed away before him. His mother was a woman of truth. They had both to eat their (daily) food. See how God makes His signs clear to them; yet see in what ways they are deluded away from the truth!"
(Qur'an 5:75)
"When Jesus came with Clear Signs, he said: 'Now I have come to you with Wisdom, and in order to make clear to you some of the (points) on which you dispute. Therefore, fear God and obey me. God, He is my Lord and your Lord, so worship Him -- this is a Straight Way.' But sects from among themselves fell into disagreement. So woe to the wrongdoers, from the penalty of a Grievous Day!" (43:63-65)
"He [Jesus] said: 'I am indeed a servant of God. He has given me revelation and made me a prophet; He has made me blessed wheresoever I be; and He has enjoined on me prayer and charity as long as I live. He has made me kind to my mother, and not overbearing or miserable. So peace is on me the day I was born, the day that I die, and the day that I shall be raised up to life (again)!'
Such was Jesus the son of Mary. It is a statement of truth, about which they (vainly) dispute. It is not befitting to (the majesty of) God that He should beget a son. Glory be to Him! When He determines a matter, He only says to it, 'Be,' and it is"
(19:30-35).
And [beware the Day] when Allah will say, "O Jesus, Son of Mary, did you say to the people, 'Take me and my mother as deities besides Allah ?'" He will say, "Exalted are You! It was not for me to say that to which I have no right. If I had said it, You would have known it. You know what is within myself, and I do not know what is within Yourself. Indeed, it is You who is Knower of the unseen.
I said not to them except what You commanded me - to worship Allah , my Lord and your Lord. And I was a witness over them as long as I was among them; but when You took me up, You were the Observer over them, and You are, over all things, Witness.
If You should punish them - indeed they are Your servants; but if You forgive them - indeed it is You who is the Exalted in Might, the Wise.
Allah will say, "This is the Day when the truthful will benefit from their truthfulness." For them are gardens [in Paradise] beneath which rivers flow, wherein they will abide forever, Allah being pleased with them, and they with Him. That is the great attainment.
To Allah belongs the dominion of the heavens and the earth and whatever is within them. And He is over all things competent.
[Qur'an 5: 116-20]