"Repay to Caesar what belongs to Caesar and to God what belongs to God." In the conclusion of the parable of the tenants (cf. Mark 12:1-12), we are told that the religious leaders sought to arrest Jesus after realizing that the parable was talking about them. And although they didn’t arrest him for fear of the crowds, it appears they were not yet done with him. They were determined to even the scores, even if it meant upping their game. In today’s Gospel passage, we see them resorting to wanting to trap Jesus in his speech. And I must give them credit for their fast thinking. The religious Jesus had known Jesus by now. They knew where he stood on the various topics that affected their society. They had done their research and were sure that whichever way Jesus answered the question they had framed for him, he was sure to annoy somebody. But they had underestimated Jesus, for he found a way of answering their question without biting their bait.
The above response by Jesus to the question that was supposed to ensnare him has become a popular saying. It is today quoted to show a separation that must exist between Church and State, as well as to express the presumed separation between the spiritual from the corporal. It is also used as an exhortation for responsible participation in public/state responsibilities. Whichever way we tend to use it, there is always the danger of making an inference that Jesus himself sanctioned such separations, or that Jesus did see the importance of separating the Church from the State or the corporal from the spiritual. However, I would think that this is far from what Jesus had in mind. His detractors, those who wanted to trap him, wanted him to fall into this same trap.
Jesus didn’t say that the denarius belonged to Caesar. He also didn’t say that it belonged to God. By telling them to give Caesar what belongs to Caesar and to God what belongs to God, Jesus was simply saying that there's nothing that absolutely belongs to Caesar that doesn't belong to God. For there is nothing that we have or do that is absolutely ours. All that we have has been given us by God. Whatever I give back to Caesar, I do because God enables me to do it. Actually, God wants me, as a responsible child of God, to do it. I am God's.  It is me - in my entirety, both body and spirit, that belongs to God. Giving back to God what belongs to God means, therefore, that I give myself back to God. Not only a part of me, not only my soul, but me in my entirety. And that includes what I think, say, or do. Giving back to Caesar is part of what I do. Giving back to Caesar is part of giving back to God.