And spake boldly - He openly defended the doctrine that Jesus was the Messiah.
In the name ... - By the authority of the Lord Jesus.
Against the Grecians - See the word “Grecians” explained in the notes on Acts 6:1. It means that he not only maintained that Jesus was the Christ in the presence of those Jews who resided at Jerusalem, and who spoke the Hebrew language, but also before those foreign Jews who spoke the Greek language, and who had come up to Jerusalem. They would be as much opposed to the doctrine that Jesus was the Christ as those who resided in Jerusalem.
They went about - They sought to slay him; or they formed a purpose to put him to death as an apostate. See Acts 9:23.