Let the nations be glad and sing for joy, for you judge the peoples with equity and guide the nations upon the earth. (Psalm 67:4)
In the time of kings, people had no control over who ruled over them, and the rights of monarchs were near absolute. Wicked kings would pervert justice, take bribes, and promote the well-being of those he favored—and there was nothing you could do about it.
In that way, the arrival of a foreign king could be good news. If he was a righteous king, or at least a king who saw the benefits of a fair society, then you would have the prospect of living in peace. If he judged impartially and guided the kingdom into prosperity then it was good for the people who lived under his rule—even if he was a foreigner.
Jesus was the Jewish Messiah, their anointed king. But he has designs on the whole of the earth. He is a conquering king. But he doesn't establish his kingdom through the weapons of war. Instead, his weapon is the good news of the gospel, and by it he intends to take over the world, to rule as its righteous and rightful king.
And we are soldiers in his army, equipped with the spiritual weapons of war (see Ephesians 6). And our two greatest weapons are the gospel message and prayer. We speak and we pray "Thy kingdom come, thy will be done on earth as it is in heaven," and as each person turns their loyalties over to Jesus, the world is brought more and more into conformity with his righteous reign.
That is good news for the nations and we can be glad that a righteous king has come.
Who are you praying for today?