When they heard this, they were enraged and wanted to kill them. But a Pharisee in the council named Gamaliel, a teacher of the law held in honor by all the people, stood up and gave orders to put the men outside for a little while. And he said to them, “Men of Israel, take care what you are about to do with these men. For before these days Theudas rose up, claiming to be somebody, and a number of men, about four hundred, joined him. He was killed, and all who followed him were dispersed and came to nothing. After him Judas the Galilean rose up in the days of the census and drew away some of the people after him. He too perished, and all who followed him were scattered. So in the present case I tell you, keep away from these men and let them alone, for if this plan or this undertaking is of man, it will fail; but if it is of God, you will not be able to overthrow them. You might even be found opposing God!” So they took his advice. (Acts 5:33-39)
At the time it have been offered merely as a bit of practical advice, but like Caiaphas before the crucifixion the words of Gamaliel are no less than prophetic. Other zealots and false messiahs had gathered following before the time of Jesus and many would come after. In A.D. 69 they managed to raise an army and the hopes of Israel for independence, prompting Rome to respond with great force. What resulted in A.D. 70 was the destruction of the Jerusalem temple and the diaspora, or dispersion of the Jews across the Roman Empire. Gamaliel wisely suggested a wait-and-see approach. If the Apostles were merely following another man, then nothing would come of it. It wouldn’t be the first group of faithful believers to come to nothing. If, however, the Jesus movement was of God then was nothing the Pharisees could do to stop it. You might, he warned, even be found opposing God. That’s actually a little more insight than Caiaphas had.
The court took his advice, by the way, and did not execute the Apostles. In the verses that follow 39 they were beaten and commanded not to continue preaching Jesus. They not only continued, but in very 42 “And every day, in the temple and from house to house, they did not cease teaching and preaching that the Christ is Jesus.”