Remember, you are mortal.
When the ancient Romans paraded a victorious general through the streets to herald a recent conquest, a slave was assigned to stand behind him with a garland and recite the phrase "memento mori." So great was the temptation for a leader to believe in his own success that it required a reminder—at the very moment of his greatest adulation—that before long he too would become worm food.
I don't expect American political parties to do the same for their just-crowned presidential nominees, but there's something to be said for one's friends providing a dose of reality. Over time the Romans neglected this practice, trading humility for empire. After just two Caesars, their third declared himself a god, taking the title "Augustus".
This was the coin handed to Jesus by the Pharisees, prompting him to famously ask: "Whose inscription is this? And whose image?" The obvious answer to both questions was "Caesar's", and we all know the Lord's reply: "Render unto Caesar what is Caesar's." That's why Christians are careful to pay taxes levied by governments. But Jesus didn't stop there, despite having delivered one of the most famous phrases ever spoken. His next words are often treated as a codicil: like they're an afterthought belonging to a totally different discussion. But they're not.
Jesus is still talking about Caesar and money and taxes when he concludes his declaration: "...and unto God what is God's." Remember who accompanied the Pharisees to trap Jesus about paying the Imperial Tax? Herodians; political allies of the Roman Tetrarch Herod Antipas...the man who beheaded Jesus' own cousin. But these guys are still God-fearing Jews, right? So what is Jesus driving at? Two things...
One: Caesar is not God. This should have been an unremarkable statement to the powerful men surrounding Jesus that day. But note the Herodians' reaction to these words: "...they were amazed." Really? How come? Sure, Caesar had claimed on this coin to be God, but Jesus is talking to Jews inside the Hebrew Temple, days before Passover. They all knew Caesar wasn't God, didn't they? The Pharisees certainly should have known that; the Herodians...maybe not. They had aligned themselves with Rome through Herod, and were very close to abandoning the God of Abraham, Isaac and Israel.
Look, the Jews at this time were demoralized. It had been 400 years since God had sent them a prophet. In the absence of a clear word from heaven, they were tempted to think crazy thoughts: maybe Herod is the Messiah. Maybe what Moses and the prophets wrote isn't true. Maybe we ought to ally with the regime in power and stop trying to stand apart from everybody else. But Jesus' words were a smack upside the head to that kind of thinking. Snap out of it!
Two: if Caesar's image on a coin obliges you to pay him tribute, whose image is on you? Wait—what? The Jewish leaders were stunned by this breathtaking simile. Jesus' analogy instantly took them to the very first chapter of the very first book of their revered Torah "Let us make man in our image..."
Man-made money is artificial—created by governments seeking honor and permanence (think of whose image is on your currency). It also allows them to secretly enrich state coffers without levying more taxes—an action which erodes the value of the coins in your pocket. If you are part of an economy using fiat money (ie: not gold), you owe the potentates whose faces are on that money a piece of their action.
But people are God-made—they're real. My very personhood has been branded as property of the Almighty One. He has stamped his image on me and given very detailed instructions about what I owe in return. One day I will die, taking with me none of this world's goods. At that point I better have figured out what it means to lay up treasure in heaven.