To follow up from the previous post, Jesus is not talking about taxes.
Marshall McLuhan was noted for saying a number of things about communication, perhaps none more famous than "the medium is the message".
This next quote either is hyperbole or is exactly how McLuhan feels about the power of the medium when he says the content of a message "has about as much importance as the stenciling on the casing of an atomic bomb.”
The point being that the medium you use to convey a message carries more power than the content of the message. This is in part why when you talk bad about your family it is much more acceptable than if I talk bad about your family - even if we say the exact same words. This is another reason why people cite Bible passages in order to justify their positions. If you have the medium of scripture then it carries with is additional weight than if a person shares their thoughts. The medium is a very powerful voice in the message.
And so when we read that Caesar would put his image on the coins of the empire, then the coin is the medium of the message of Caesar. Since coins are used in every transaction in all aspects of the Empire, since nothing can happen without the shiny head of Caesar being involved, the message of Caesar is clear - I am present everywhere and I am all powerful. My image is what makes it possible to do anything. I am the god of these parts and I will change the world through these coins.
When Jesus reminds us that humanity is made with the image of God impressed upon us then it also is worth noting that we are the mediums of God message. And through this medium of humanity God's message is clear - I am focused on relationship not on economics. At times I am strong and at other times I am weak. I bleed and cry and shout. My image makes it possible for life to be made. I am the god of these parts and I will change the world though these people.
You and I are God's medium for God's message. Christians articulate that the Good News is not just that Christ died for us but that God lived for us. God could have chosen any sort of medium to convey the Good News. God chose a human being.
And that medium, Jesus, changed the world. We do not have every word that Jesus said but the content of his message is as important as the stenciling on a bomb. It was his life that was the message. It was the way he lived that changed the world.
McLuhan popularized it, but God created the fact that the Medium is the Message.