“For in truth in this city against your holy Servant Jesus, whom you anointed, both Herod and Pontius Pilate, with the Gentiles and the peoples of Israel, were gathered together, to do whatever your hand and your council foreordained to come about.”
Now the same situation was being repeated. The kings and governors of the earth (Herod and Pilate) and the Gentiles and peoples (of Israel), had raised themselves up into opposition against God's holy Servant Jesus. They had mobilised in order to rid the world of Him. But although they did not realise it they had done it at God's behest. They were as puppets in His hands, responding to His pulling of the strings. They were only doing what God's hand and council had foreordained. For His death had been necessary in order to propitiate for the sins of the whole world.
So Pilate, and Herod, together will all peoples, were under God's control and did His will in such matters. It is slightly unusual for Luke to put blame on Pilate but all he is necessarily saying is that Pilate was involved in what happened, even though he did not like it, which was undeniable. Without his say-so, albeit forced from him, it could not have happened. Note that here the peoples of Israel are included among the enemies of the Lord's Anointed. This can only be because the King now has a new people of Israel to guard and watch over. The false vine has been replaced by the true vine, the true vine of ‘Christ at one with His people' (John 15:1-6; Ephesians 2:11-22). The church is God's new people. The old Israel has been cut off.