Blasphemy was no small charge. Indeed, Martin Luther has written [I think it is in the Large Catechism] that all of the commandments are a meditation on the first commandment: You shall have no other gods before Me. This charge of blasphemy was central as the early church wrestled with the identity of this Messiah Jesus. If God is One and the only one worthy of worship and yet there is this Jesus, He must be in some intimate way, be God, for if He is not, we have committed the sin of idolatry.
The dark twist of course, for those of us who confess Jesus to be non only the Messiah but God incarnate, is what is done to him: spitting on Him, striking him, slapping him, mocking him. The one charged with blasphemy is blasphemed.