Luke 20:26

they marvelled at his answer Comp. Luke 2:47. They thought that escape was impossible for Him; and yet He instantly shatters their deeply-laid plot to pieces by shewing that they Pharisees and Herodians alike had absolutely decided the question already(according to their own rule "He whose coin is current is king of the land"), so that there is no need for Him to give any opinion whatever about it. The point was this, their national acceptance of Caesar's coinage was an unanswerable admission of Caesar's right. Tribute to them was no longer a cheerful offering, but a legal due; not a voluntary gift, but a political necessity. The very word He used was decisive. They had asked "Is it lawful to give(dounai)?" He answers, -Give back" (apodote).By using these coins they all alike admitted that -they had no king but Caesar." The Christians understood the principle perfectly (1 Peter 2:13-14) as the ancient Jews had done (Jeremiah 27:4-8). Yet these hypocrites dared to shout three days afterwards that Jesus -had forbidden to give tribute to Caesar!"