The Lord Reigns.
Say among the nations, “The Lord reigns; The world also is firmly established, It shall not be moved; He shall judge the peoples righteously.” Psalm 96:10 NKJV
We have here instructions given to those who were to preach the gospel to the nations what to preach, or to those who had themselves received the gospel what account to give of it to their neighbours, what to say among the heathen; and it is an illustrious prophecy of the setting up of the kingdom of Christ upon the ruins of the devil's kingdom, which began immediately after his ascension and will continue in the doing till the mystery of God be finished.
Let it be told that the Lord reigns, the Lord Christ reigns, that King whom God determined to set upon his holy hill of Zion. See how this was first said among the heathen by Peter, Acts 10:42. Some of the ancients added a gloss to this, which by degrees crept into the text, The Lord reigneth from the tree (so Justin Martyr, Austin, and others, quote it), meaning the cross, when he had this title written over him, The King of the Jews. It was because he became obedient to death, even the death of the cross, that God exalted him, and gave him a name above every name, a throne above every throne. Some of the heathen came betimes to enquire after him that was born King of the Jews, Matthew 2:2. Now let them know that he has come and his kingdom is set up.
Let it be told that Christ's government will be the world's happy settlement. The world also shall be established, that it shall not be moved. The natural world shall be established. The standing of the world, and its stability, are owing to the mediation of Christ. Sin had given it a shock, and still threatens it; but Christ, as Redeemer, upholds all things, and preserves the course of nature. The world of mankind shall be established, shall be preserved, till all that belong to the election of grace are called in, though a guilty provoking world. The Christian religion, as far as it is embraced, shall establish states and kingdoms, and preserve good order among men. The church in the world shall be established (so some), that it cannot be moved; for it is built upon a rock, and the gates of hell shall never prevail against it; it is a kingdom that cannot be shaken.
Let them be told that Christ's government will be incontestably just and righteous: He shall judge the people righteously. judge the world with righteousness, and with his truth, Judging is here put for ruling; and though this may be extended to the general judgment of the world at the last day, which will be in righteousness (Acts 17:31), yet it refers more immediately to Christ's first coming, and the setting up of his kingdom in the world by the gospel. He says himself, For judgment have I come into this world (John 9:39; 12:31), and declares that all judgment was committed to him, John 5:22, 27. His ruling and judging with righteousness and truth signify, That all the laws and ordinances of his kingdom shall be consonant to the rules and principles of eternal truth and equity, that is, to the rectitude and purity of the divine nature and will. That all his administrations of government shall be just and faithful, and according to what he has said. That he shall rule in the hearts and consciences of men by the commanding power of truth and the Spirit of righteousness and sanctification. When Pilate asked our Saviour, Art thou a king? he answered, For this cause came I into the world, that I should bear witness unto the truth (John 18:37); for he rules by truth, commands men's wills by informing their judgments aright.
Let them be told that his coming draws nigh, that this King, this Judge, standeth before the door; for he cometh, for he cometh. Enoch, the seventh from Adam, said so. Behold, the Lord cometh, Jude 14. Between this and his first coming the revolutions of many ages intervened, and yet he came at the set time, and so sure will his second coming be; though it is now long since it was said, Behold, he comes in the clouds (Revelation 1:7) and he has not yet come. See 2 Peter 3:4. - Matthew Henry