"And the angel said unto her, Fear not, Mary: for thou hast found favour with God. And, behold, thou shalt conceive in thy womb, and bring forth a son, and shalt call his name JESUS. He shall be great, and shall be called the Son of the Highest: and the Lord God shall give unto him the throne of his father David: And he shall reign over the house of Jacob for ever; and of his kingdom there shall be no end."
On the death of his father in 1643, Louis XIV was named king of France, though he was just four years old. His mother headed a regency council which effectively governed the nation until Louis came of age, but he was the king—and would remain so for seventy-two years. Yet despite his lengthy time on the throne, the Sun King eventually reached the end of his life. He passed the throne on to his son, but his grandson, Louis XVI was deposed and executed in the French Revolution, ending the monarchy for good.
Every human kingdom, empire, and nation is limited. Some of the greatest and most powerful empires of history are now nothing more than footnotes in academic texts. Even in our lifetimes, nations have risen and fallen. All the works and powers of man are temporary at best. In contrast, the Bible repeatedly tells us that God's kingdom has no end. Like Him, it is eternal.
Our focus in this temporal world is meant to be on the eternal. Rather than spending our time building things that will soon vanish, we should be focused on what will last—the kingdom of God. “For here have we no continuing city, but we seek one to come” (Hebrews 13:14). No investment that we make of our time, energy, and resources in God's work will be wasted because it is placed into an eternal kingdom. This is how our lives should be spent.
Only by building the eternal kingdom of God can we do something that will truly last.