They sent some Pharisees and Herodians to him to ensnare him in his speech. They came and said to him, "Teacher, we know that you are a truthful man and that you are not concerned with anyone's opinion. You do not regard a person's status but teach the way of God in accordance with the truth. Is it lawful to pay the census tax to Caesar or not? Should we pay or should we not pay?" Knowing their hypocrisy he said to them, "Why are you testing me? Bring me a denarius to look at." They brought one to him and he said to them, "Whose image and inscription is this?" They replied to him, "Caesar's." So Jesus said to them, "Repay to Caesar what belongs to Caesar and to God what belongs to God.' They were utterly amazed at him. (Mk 12:13-17)
The discussion is between Jesus and the Pharisees and Herodians. Jesus is presented as a person who is truthful, who is not concerned with anyone’s opinion, who does not regard person’s status, and teaches the way of God in accordance with the truth. This is a beautiful description of the character of Jesus. And the other group is presented as hypocrites (insincere; double standard). Jesus replies these characters as well.
Though Jesus came to preach the Kingdom, and preach God in truth; yet he argues with hypocrites and tries to prove them wrong. The Pharisees were trying to put the religion against to the state. Yet their ultimate aim was to test Jesus and put him into difficulties in speech.
The teaching of Jesus in this passage is that the state and the religion are not opposed to each other. Each has its role to play. Religion and society are the two sides of the same coin. Religion should purify the society and the society should allow the religion to present God experience to the people.