"Tell us, therefore, what do You think? Is it lawful to pay taxes to Caesar, or not?” Matthew 22:17
The Pharisees had already decided a question, yet they sent their disciples to test Jesus. Which means they didn't already believe that He was Messiah. The had an answer they thought right and true, but they wanted to hear this man agree with them, or refute their right with His wrong. They were of course certain that they did not have a wrong. This was a problem.
Jesus, as you can read in the remainder of the story, was not fooled by the junior Pharisees in the least. He gave them an answer that left them marveling. No doubt the professors back at Pharisee U. gave them a failing grade upon their return. The possibility that Jesus could be Messiah just did not seem to occur to the Pharisees at any point in the Gospels.
Therefore, if the world continues to test your witness and steadfastly refuses to believe your account of our Lord's salvation, then you walk in good company, for the Pharisees refused to believe in Jesus even after He died and rose again. Peter's ministry did not shake their unbelief after the outpouring of the Holy Spirit. Paul's dramatic conversion did not shock their rock-solid hearts after their star met the Christ on the road to Damascus. The Pharisees back in their day were as firm in their unbelief as we would like to be in our faith!God's grace to you, Bucky