Jesus let the coin speak. Instead of giving a quick yes or no, He made His questioners say out loud whose coin they were carrying. Gill notes that the image showed it was a Roman coin, "for the Jews, though they put inscriptions, yet no images on their coin." Matthew Henry points out that accepting a coin as the lawful money of a country "is an implicit submission to those powers." The men who asked whether tribute was lawful already had Caesar's money in their hands. The question led them to answer their own trap.

"They say unto him, Caesar's" (Matthew 22:21). Jesus built His answer on their own word: "Render therefore unto Caesar the things which are Caesar's; and unto God the things that are God's" (Matthew 22:21). "When they had heard these words, they marvelled, and left him, and went their way" (Matthew 22:22). Mark and Luke record the same answer and the same amazement (Mark 12:16-17; Luke 20:24-26).

The "penny" was a Roman denarius (Barnes). "Image" is eikon, a likeness, and "superscription" is epigraphe, an inscription. Barnes explains that the likeness of the reigning prince was probably struck on the coins, and that the superscription gave the name and titles of the emperor.

This set the coin apart from Jewish money. Gill notes that Jewish coins carried inscriptions but no images. Matthew Henry adds that the emperor's image and superscription were "the warrant of the public faith," the sign that stood behind the money's value.

The question opened the way to a principle much larger than one tax. Caesar's image on the coin showed it belonged in Caesar's realm. But Jesus did not stop there: "and unto God the things that are God's." The second half is the weightier one.

Barnes offers two readings of that second half. It may refer to the annual tribute for the temple service, or it may mean that they should give "their hearts, lives, property, and influence, all to God, as his due." Matthew Henry hears in it a quiet rebuke: while they argued about their civil liberties, they had lost the life and power of religion and needed reminding of their duty to God. Either way, Jesus moved the conversation from what Rome could demand to what God rightly claims.