Jesus confirmed that He was the Messiah. But this can't be a blasphemy as the Jews were waiting for him. Jesus confirmed that He was the Son of God. But a lot of people in the old Testament were called Son of God. Jesus confirmed that He was sitting right next to the Power. Was this the main reason that He committed blasphemy?
The charge of blasphemy in the Gospels, both during Jesus' ministry and in his trial, does not refer to the specific and technical definition of blasphemy, which according to the Mishna, tractate Sanhedrin, Chapter VII, Mishna VI, requires the blasphemer to have mentioned the Name, i.e. the Tetragrammaton, which Jesus never did. Rather, the charge of blasphemy refers to Jesus' claim of divinity. Below I present the Gospel passages that show this to be the case both during Jesus' ministry and in his trial.
a. Charges of blasphemy during Jesus' ministry
The meaning of the charge of blasphemy is clear in the very first encounter of Jesus and the scribes recorded in all synoptic Gospels, when Jesus forgives the sins of a paralytic in Capernaum and then heals him:
And when Jesus saw their faith, he said to the paralytic, "Son, your sins are forgiven." Now some of the scribes were sitting there, questioning in their hearts, "Why does this man speak like that? He is blaspheming! Who can forgive sins but God alone?" (Mk 2:5-7; also Mt 9:2-3 and Lk 5:20-21).
In John, the substance of the charge against Jesus is clear in all three occasions when "the Jews", not the Sanhedrin, decided, or actually tried, to kill Him during his ministry. Of these three occasions, only in the third is that charge given a name, which is precisely blasphemy:
This was why the Jews were seeking all the more to kill him, because not only was he breaking the Sabbath, but he was even calling God his own Father, making himself equal with God. (Jn 5:18)
Jesus said to them, "Truly, truly, I say to you, before Abraham was, I am." So they picked up stones to throw at him, but Jesus hid himself and went out of the temple. (Jn 8:58-59)
(Jesus said) "I and the Father are one." The Jews picked up stones again to stone him. Jesus answered them, "I have shown you many good works from the Father; for which of them are you going to stone me?" The Jews answered him, "It is not for a good work that we are going to stone you but for blasphemy, because you, being a man, make yourself God." (Jn 10:30-33)
b. Charge of blasphemy in Jesus' trial
I will quote the text in Mark as it is more likely to have greater literal fidelity to the words spoken, as Simon Peter was a direct witness of the trial and Mark composed his Gospel from what he heard from Peter, most probably in Jerusalem in the 40's:
But he remained silent and made no answer. Again the high priest asked him, "Are you the Christ, the Son of the Blessed?" And Jesus said, "I am, and you will see the Son of Man seated at the right hand of Power, and coming with the clouds of heaven." And the high priest tore his garments and said, "What further witnesses do we need? You have heard his blasphemy. What is your decision?" And they all condemned him as deserving death. (Mk 14:61-64)
I hypothesize that, while Caiaphas asked his question in Aramaic, Jesus answered in Hebrew, both the "I am" and the following scriptural quote, so that his "I am" was clearly understood by those knowledgeable in the Torah as the "Ehyeh" of Ex 3:14, the Name of God in first person, i.e. when used by God Himself. This would have been an explicit claim of divinity in addition to the one implied in the following combined quote of Psalm 110:1 and Dan 7:13.
"They were expecting someone taller"
The Messiah that was expected was someone from the line of King David, who was a very strong King who had defeated the enemies of Israel. It is very understandable, if one puts one's self in the shoes of the Sanhedrin, to assess the claims that Jesus was the Messiah -- the anointed one -- in an unfavorable light given that he did not meet their expectation.
It was then logical for them to conclude, based on their expectation, that this prophet/rabbi was not who he, and his followers, said he was. So if he wasn't, then it would be blasphemy for Jesus to behave as described in Mark 2:5-7
And when Jesus saw their faith, he said to the paralytic, "Son, your sins are forgiven." Now some of the scribes were sitting there, questioning in their hearts, "Why does this man speak like that? He is blaspheming! Who can forgive sins but God alone?"
To attribute to one's self that which is God's alone to do or give is to assert being divine. Again, under the logic of "he can't be the Messiah since he isn't behaving like King David" he can only be blaspheming in a case like the above interaction from their point of view.
John 19:6-7 (DRB)
When the chief priests, therefore, and the servants, had seen him, they cried out, saying: Crucify him, crucify him. Pilate saith to them: Take him you, and crucify him: for I find no cause in him. The Jews answered him: We have a law; and according to the law he ought to die, because he made himself the Son of God.
Elsewhere, we see they desired to kill Jesus for claiming divinity before this:
Hereupon therefore the Jews sought the more to kill him, because he did not only break the sabbath, but also said God was his Father, making himself equal to God.
And again, a similar incident,
The Jews answered him: For a good work we stone thee not, but for blasphemy; and because that thou, being a man, maketh thyself God.
Again, at the Cross:
He trusted in God; let him now deliver him if he will have him; for he said: I am the Son of God.
This appears overwhelmingly to have been their main issue.
Church Fathers of course viewed Wisdom 2:12-20 as prophesying this:1
Let us therefore lie in wait for the just one,2 because he is not for our turn, and he is contrary to our doings, and upbraideth us with transgressions of the law, and divulgeth against us the sins of our way of life. 13 He boasteth that he hath the knowledge of God, and calleth himself the son of God. 14 He is become a censurer of our thoughts. 15 He is grievous unto us, even to behold: for his life is not like other men's, and his ways are very different. 16 We are esteemed by him as triflers, and he abstaineth from our ways as from filthiness, and he preferreth the latter end of the just, and glorieth that he hath God for his father. 17 Let us see then if his words be true, and let us prove what shall happen to him, and we shall know what his end shall be. 18 For if he be the true son of God, he will defend him, and will deliver him from the hands of his enemies. 19 Let us examine him by outrages and tortures, that we may know his meekness and try his patience.3 20 Let us condemn him to a most shameful death: for there shall be respect had unto him by his words.4
1 e.g. Epistle of Barnabas, vi. 7; Clement of Alexandria, Stromata, 14; Lactanius, Divine Institutes, iv. 16; Epitome, 45; Cyprian, Treatise 12, Book ii. 14; Hyppolytus, Expos. Treatise Against the Jews, 9; Augustine, Expos. Psalm 53, 3etc.
2 Jas 5:6; cf. Acts 3:14; 7:52; 22:14—"τὸν δίκαιον"
3 Mt 26:67
4 Jn 11:46-48,53
Christ did not commit blasphemy. The Sanhedrin charged Him with blasphemy because they did not believe Him to be the Son of God. Caiaphas' anger is the best clue.
"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.
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.
65 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." (KJV)
Coming upon the clouds of heaven was judgment language from OT prophesy, and was pronounced by the prophets as the presence of God.
"10 And he rode upon a cherub, and did fly: yea, he did fly upon the wings of the wind.
11 He made darkness his secret place; his pavilion round about him were dark waters and thick clouds of the skies.
12 At the brightness that was before him his thick clouds passed, hail stones and coals of fire." (KJV)
"`I was seeing in the visions of the night, and lo, with the clouds of the heavens as a son of man was [one] coming, and unto the Ancient of Days he hath come, and before Him they have brought him near." (YLT)
"Behold, he shall come up as clouds, and his chariots shall be as a whirlwind: his horses are swifter than eagles. Woe unto us! for we are spoiled." (KJV)
See also Job 22:14, Joel 2:2, Nah. 1:3, Zeph. 1:15.
Caiaphas knew that Christ had just pronounced judgment upon him and the Sanhedrin. He was so angry that he tore his clothes. As only God can pronounce judgment, and as they did not believe Christ to be the Son of God blessed with the authority from God (Matt. 28:18), then they convicted Him of blasphemy, which had been their chief aim all along.
All bold emphasis is mine.