by Thomas Watson
The next attribute is God's unchangeableness.
"I am the Lord, and I do not change." Malachi 3:6
God is unchangeable in his nature, and in his decree.
I. God is unchangeable in his NATURE.
1. There is no eclipse of his brightness.
2. No end put to his being.
 There is no eclipse of his brightness. His essence shines with a fixed luster. "Who does not change like shifting shadows," James 1:17. "You remain the same, and your years will never end," Psalm 102:27. All created things are full of vicissitudes. Princes and emperors are subject to change. Sesostris, an Egyptian prince, having subdued many kings in war, made them draw his chariot, like horses, as if he intended them to eat grass, as God did King Nebuchadnezzar. The crown has many successors. Kingdoms have their eclipses and convulsions. What has become of the glory of Athens? The pomp of Troy? [Now corn grows, where the great city of Troy once stood]. Though kingdoms have a head of gold, they have feet of clay.
The heavens change. "They will perish, but you remain; they will all wear out like a garment. Like clothing you will change them and they will be discarded. But you remain the same, and your years will never end." Psalm 102:26-27. The heavens are the most ancient records, where God has written his glory with a sunbeam—yet these shall change. Though I do not think they shall be destroyed as to their substance—yet they shall be changed as to their qualities; they shall melt with fervent heat, and so be more refined and purified. 2 Peter 3:12. Thus the heavens shall be changed—but not he who dwells in heaven. "I am the Lord, and I do not change."
The best saints have their eclipses and changes. Look upon a Christian in his spiritual estate, and he is full of variation. Though the seed of grace does not die—yet its beauty and activity often wither. A Christian has his anguish fits in piety. Sometimes his faith is at a high tide—and sometimes low ebb; sometimes his love flames—and at another time is like fire in the embers, and he has lost his first love. How strong was David's grace at one time! "God is my rock, in him will I trust." At another time he says, "I shall one day perish by the hand of Saul." What Christian can say he does not find a change in his graces; that the bow of his faith never unbends, the strings of his violin never slacken? Surely we shall never meet with such Christians until we meet them in heaven! But God is without any shadow of change.
The angels were subject to change; they were created holy—but mutable. "The angels which kept not their first estate." Jude 6. These morning stars of heaven were falling stars. But God's glory shines with a fixed brightness. In God there is nothing which can change, for better or worse. He cannot change for the better—because then he would not now be perfect. He cannot change for the worse—for then he would cease to be perfect. He is immutably holy, immutably good; there is no shadow of change in him.
But when Christ, who is God, assumed the human nature—was there a change in God?
If the divine nature had been converted into the human, or the human into the divine, there would have been a change—but they were not. The human nature was distinct from the divine nature. Therefore there was no change. A cloud over the sun makes no change in the the sun. Just so, though the divine nature is covered with the human nature, it makes no change in the divine nature.
 There is no end put to his being. "Who alone has immortality." The Godhead cannot die. An infinite essence cannot be changed into finite; and God is infinite. He is eternal, consequently he is not mortal. To be eternal and mortal is a contradiction.
Use one: See the excellence of the divine nature in its immutability. This is the glory of the Godhead. Mutableness denotes weakness, and is not in God, who is "the same, yesterday, and today, and forever." Men are fickle and mutable, like Reuben, "unstable as water." Men are changeable in their principles. If their faces altered as fast as their opinions—we would not recognize them. Men are changeable in their resolutions; just as the wind that blows in the east, presently turns about to the west. They resolve to be virtuous—but quickly give up of their resolutions. Their minds are like a sick man's pulse, which alters every half hour. The apostle Jude compares them to waves of the sea, and wandering stars. They are not pillars in God's temple—but reeds shaken by the wind. Others are changeable in their friendship. They quickly love—and quickly hate. Sometimes they will press you to their bosom; later they will excommunicate you out of their favor. They change as the chameleon, into several colors. But God is immutable—he does not change.
Use two: See the vanity of the creature. There are changes in everything, but in God. "Lowborn men are but a breath, the highborn are but a lie; if weighed on a balance, they are nothing; together they are only a breath." Psalm 62:9. We look for more from the creature, than God has put in it. The creature has two evils in it—it promises more than we find—and it fails us when we most need it. A man desires to have his corn harvested—but the rain falls; the mariner is for a voyage—but the wind does not blow, or is contrary; one depends upon another for the payment of a promise, and he fails, and is like a foot out of joint. Who can find a fixed stability in the vain creature? It is as if one should build houses on the sand, where the sea comes in and overflows. The creature is true to nothing but deceit—and is constant only in its disappointments. It is no more astonishing to see changes in the creature, than to see the moon dressing itself in a new shape and figure. Expect to meet with changes in everything, but God.
Use three: Comfort to the godly.
(1.) In case of losses. If an estate, you are almost boiled away to nothing, and if you lose friends by death—there is a double eclipse. But the comfort is—God is unchangeable. I may lose these things—but I cannot lose my God; he never dies. When the fig-tree and olive-tree failed, God did not fail. "I will rejoice in the God of my salvation." Flowers in the garden die—but a man's portion remains. Just so, outward things die and change—but "you are the strength of my heart, and my portion forever."
(2.) In case of sadness of spirit. God seems to cast off the soul in desertion. "My Beloved had withdrawn himself." Yet, God is unchangeable. He is immutable in his love; he may change his countenance—but not his heart! "I have loved you with an everlasting love." Jer 31:1. Hebrew—a love of eternity. If once God's electing love rises upon the soul—it never sets. "Though the mountains be shaken and the hills be removed, yet my unfailing love for you will not be shaken nor my covenant of peace be removed—says the Lord, who has compassion on you." Isaiah 54:10. God's love stands firmer than the mountains. His love to Christ is unchangeable; and he will no more cease loving believers, than he will cease loving Christ.
Use four: Of exhortation. Get a saving interest in the unchangeable God, then you are as a rock in the sea—immoveable in the midst of all changes.
How shall I get a part in the unchangeable God?
By having a change wrought in you. "But you are washed—but you are sanctified." By this change we are savingly interested in the unchangeable God.
Trust to that God, who alone is unchangeable. "Cease from man," stop trusting to the reed—but trust to the Rock of ages. He who is by faith engarrisoned in God, is safe in all changes; he is like a boat that is tied to an immoveable rock. He who trusts in God, trusts in that which cannot fail him; for God is unchangeable. "I will never leave you, nor forsake you." Health may leave us, riches, friends may leave us; "but," says God, "I will never leave you; my power shall support you; my Spirit shall sanctify you; my mercy shall save you! I will never leave you!" Oh trust in this unchangeable God!
God is jealous of two things; of our love, and of our trust. He is jealous of our love, lest we love the creature more than him; therefore he makes it prove bitter. God is jealous of our trust, lest we should place more confidence in the creature, than in him, therefore he makes it prove unfaithful. Outward comforts are given us as food along the way—to refresh us, not as crutches to lean on. If we make the creature an idol, what we make our trust, God will make our shame. Oh trust in the immortal God! Like Noah's dove, we have no footing for our souls, until we get into the ark of God's unchangeableness. "Those who trust in the Lord shall be like mount Zion, which cannot be removed."
II. God is unchangeable in his DECREE. What he has decreed from eternity is unalterable. "My purpose will stand, and I will do all that I please." Isaiah 46:10. God's eternal counsel or decree, is immutable. If he changed his decree, it must be from some defect of wisdom or foresight, for that is the reason why men change their purposes; they see something afterwards, which they did not see before. But this cannot be the cause why God should alter his decree, because his knowledge is perfect—he sees all things in one entire prospect before him.
But is not God said to repent? This seems to be a change in his decree? "The Lord repented of the evil that he said he would do unto them."
Repentance is attributed to God, figuratively. "He is not a man, that he should repent." There may be a change in God's work—but not in his will. He may will a change—but not change his will. "God may change his sentence—but not his decree." A king may cause sentence to be passed upon a malefactor whom he intends to save; so God threatened destruction to Nineveh—but the people of Nineveh repenting, God spared them. Here God changed his sentence—but not his decree; it was what had lain in the womb of his purpose from eternity.
But if God's decree is unchangeable, and cannot be reversed, then to what purpose should we use the means? Our endeavors towards salvation cannot alter his decree.
The decree of God does not affect my endeavor; for he who decreed my salvation, decreed it in the use of means; and if I neglect the means I reprobate myself. No man argues thus: "God has decreed how long I shall live, therefore I will not use any means to preserve my life, I will not eat and drink." As God has decreed the length of my life, in the use of means—so God has decreed my salvation in the use of the Word and of prayer. As a man who refuses food murders himself—just so, he who refuses to work out his salvation destroys himself. The vessels of mercy are said to be prepared unto glory. How are they prepared, but by being sanctified? and that cannot be, but in the use of means. Therefore let not God's decree, take you off from holy endeavors. It is a good saying of Preston, "Have you a heart to pray to God? it is a sign that no decree of wrath has passed against you."
Use one: If God's decree is eternal and unchangeable, then God does not elect upon our foreseen faith, as the Arminians maintain. "The children being not yet born, that the purpose of God according to election might stand, it was said, Jacob have I loved, Esau have I hated." Romans 9:11, 13. We are not elected for our holiness—but to holiness. Eph 1:1. If we are not justified for our faith, much less are we elected for our faith. We are said to be justified through faith as an instrument—but not for faith as a cause; and, if not justified for faith, then much less elected for faith. God's decree of election, is eternal and unchangeable, and therefore depends not upon foreseen faith. "As many as were ordained to eternal life, believed." They were not elected because they believed—but they believed because they were elected.
Use two: If God's decree is unchangeable, it gives comfort in two cases.
(1.) Concerning God's providence towards his church. We are ready to quarrel with Providence, if everything does not accord with our desire. Remember God's work goes on, and nothing happens, but what he has decreed from eternity.
(2.) God has decreed troubles for the church's good. The troubles of God's church, are like the angel's troubling the water, which made way for healing his people. God has decreed troubles in the church. "His fire is in Zion, and his furnace in Jerusalem." The wheels in a watch move contrary to one another—but they all carry on the motion of the watch. Just so, the wheels of Providence often move contrary to our desires—but still they carry on God's unchangeable decree. "Many shall be made white." God lets the waters of affliction be poured on his people—to make them white. Therefore, do not murmur at God's dealings! His work goes on; nothing happens, but what he has wisely decreed from eternity. Everything shall promote God's design, and fulfill his decree.
Use three: Comfort to the GODLY in regard of their salvation. "The foundation of God stands sure, having this seal—The Lord knows those who are his." God's counsel of election is unchangeable. Once elected—forever elected. "I will not blot his name out of the book of life." The book of God's decree has no errata in it, no blottings out. Once justified, never unjustified. "Repentance shall be hid from my eyes." Hos 13:14. God never repents of his electing love. "He loved them to the end." Therefore, if you are a believer, comfort yourself with this—the immutability of God's decree.
Use four: To conclude with a word to the WICKED, who march furiously against God and his people—let them know that God's decree is unchangeable. God will not alter it, nor can they break it! While they resist God's will, they fulfill it. There is a two-fold will of God—the will of God's precept, and the will of his decree. While the wicked resist the will of God's precept, they fulfill the will of his permissive decree. Judas betrays Christ, Pilate condemns him, the soldiers crucify him; while they resist the will of God's precepts, they fulfill the will of his permissive decree. "For, in fact, in this city both Herod and Pontius Pilate, with the Gentiles and the peoples of Israel, assembled together against Your holy Servant Jesus, whom You anointed, to do whatever Your hand and Your plan had predestined to take place." Acts 4:27-28.
God commands one thing, they do the contrary. While they disobey his command, they fulfill his permissive decree. If a man sets up two nets, one of silk, the other of iron, the silken net may be broken, not the iron one. Just so, while men break the silken net of God's command, they are taken in the iron net of his decree; while they sit backward to God's precepts, they row forward to his decrees. God decrees to permit their sin, and then to punish them for their sin permitted.
Excerpt from A Body of Divinity