Jesus was sentenced to crucifixion because the rulers of the Jews conspired against him. They were envious and jealous of Jesus who was gaining many followers and these prideful men had been humbled many times by Jesus during their many debates. The Sandhedrin never charged Jesus was claiming to be "God." Rather they charged him with claiming to be the son of God (Jn 19:7). These Jews understood
their one God to be the Father and Jesus was claiming to be his son. They considered Jesus' claim to be a blasphemous sin deserving death.
And the High Priest said to him, "I adjure you by the living God, tell us if you are the Christ, the son of God." Jesus said to him, "You have said so. But I tell you, hereafter you will see the son of man seated at the right hand of Power, and coming on the clouds of heaven." Then the high priest tore his robes, and said, "He has uttered blasphemy. Why do we still need witnesses? You have now heard his blasphemy. What is your judgment?" They answered, "He deserves death." (Matthew 26:63-66)
Again the High Priest asked him, "Are you the Christ, the son of the Blessed One?" 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, "Why do we still need witnesses? You have heard his blasphemy. What is your decision?" And they all condemned him as deserving death. (Mark 14:61-64).
So when the chief priests and the officers saw him, they cried out saying, "Crucify, crucify!" Pilate said to them, "Take him yourselves and crucify him, for I find no guilt in him." The Jews answered him, "We have a law, and by that law he ought to die because he made himself out to be the son of God."
"You who would destroy the temple and build it in three days, save yourself! If you are the son of God, come down from the cross." So also the chief priests, with the scribes and elders, mocked him, saying, "He saved others; he cannot save himself. He is the King of Israel; let him come down now from the cross, and we will believe in him. He trusts in God; let God deliver him now, if he desires him; for he said, "I am the son of God.' " (Matthew 27:40-44).
When Jesus is finally charged, he is not charged with claiming to be God. He is charged with claiming to be the Son of the God of the Jews. This is quite obvious when the Jews mock him and insist that if he really is the Son of God, then his God, who they perceive is someone other than Jesus, should save him.