The next attribute is God's unchangeableness. 'I am Jehovah, I change not' (Mal. 3:6). I. God is unchangeable in his nature. II. In his decree.
I. Unchangeable in his nature. 1. There is no eclipse of his brightness. 2. No period put to his being.
 No eclipse of his brightness. His essence shines with a fixed lustre. 'With whom is no variableness, neither shadow of turning' (James 1:17). 'Thou art the same' (Ps. 102:27). All created things are full of vicissitudes. Princes and emperors are subject to mutation. Sesostris, an Egyptian prince, having subdued divers 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 is become of the glory of Athens? The pomp of Troy? jam seges est ubi Troja fuit [Now corn grows where Troy once stood]. Though kingdoms have a head of gold, they have feet of clay. The heavens change. 'As a vesture shalt thou change them, and they shall be changed' (Ps. 102:26). 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. 'With him there is no variableness, nor shadow of turning.' 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 aguish fits in religion. Sometimes his faith is at a high tide, 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! 'The God of my rock, in him will I trust' (2 Sam. 22:3). 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 viol never slacken? Surely we shall never meet with such Christians till we meet them in heaven. But God is without any shadow of turning. 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 that looks like a change, for better or worse; not better, because then he were not perfect; not 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, there was a change in God.
If the divine nature had been converted into the human, or the human into the divine, there had been a change, but they were not so. The human nature was distinct from the divine. Therefore there was no change. A cloud over the sun makes no change in the body of the sun; so, though the divine nature be covered with the human, it makes no change in the divine nature.
 There is no period put to his being. 'Who only hath immortality' (1 Tim. 6:16). The Godhead cannot die. An infinite essence cannnot be changed into finite; but God is infinite. He is eternal, ergo, 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 to-day, and for ever' (Heb. 13:8). Men are fickle and mutable, like Reuben, 'unstable as water' (Gen. 49:4). They are changeable in their principles. If their faces altered as fast as their opinions, we should not know them. Changeable in their resolutions; as the wind that blows in the east, presently turns about to the west. They resolve to be virtuous, but quickly repent of their resolutions. Their minds are like a sick man's pulse, which alters every half hour. An apostle compares them to waves of the sea, and wandering stars (Jude 13). They are not pillars in God's temple, but reeds. Others are changeable in their friendship. They quickly love and quickly hate. Sometimes they will put you in their bosom, then excommunicate you out of their favour. They change as the chameleon, into several colours, but God is immutable.
Use two: See the vanity of the creature. There are changes in everything but in God. 'Men of high degree are vanity, and men of low degree are a lie' (Ps. 62:9). We look for more from the creature than God has put in it. It has two evils in it; it promises more than we find, and it fails us when we most need it. There is failure in omni. A man desires to have his corn ground, and the water fails; the mariner is for a voyage, and 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 would look for 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 wonderful to see changes fall out here below, 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 be almost boiled away to nothing, 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 joy in the God of my salvation' (Hab, 3:18). Flowers in the garden die, but a man's portion remains; so outward things die and change, but 'thou art the strength of my heart, and my portion for ever' (Ps. 73:26). In case of sadness of spirit. God seems to cast off the soul in desertion, as in Song of Solomon 5:6: 'My Beloved had withdrawn himself;' yet he is unchangeable. He is immutable in his love; he may change his countenance, but not his heart. 'I have loved thee with an everlasting love' (Jer. 31:3). Hebrew, Olam, a love of eternity. If once God's electing love rises upon the soul, it never sets. 'The mountains shall be removed, but my loving kindness shall not depart from thee, neither the covenant of my peace be removed' (Is. 54:10). God's love stands faster 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 an interest in the unchangeable God, then thou art 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 thee. 'But ye are washed, but ye are sanctified' (1 Cor. 6:11). Whence we are changed, a tenebris ad lucem [from darkness to light], so changed, as if another soul did live in the same body. By this change we are interested in the unchangeable God.
Trust to that God only who is unchangeable. 'Cease ye from man' (Is. 2:22); leave trusting to the reed, but trust to the Rock of ages. He that is by faith engarrisoned in God, is safe in all changes; he is like a boat that is tied to an immoveable rock. He that trusts in God, trusts in that which cannot fail him; he is unchangeable. 'I will never leave thee, nor forsake thee' (Heb. 13:5). Health may leave us, riches, friends may leave us, but, says God, I will not leave thee; my power shall support thee; my Spirit shall sanctify thee; my mercy shall save thee; I will never leave thee. 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; and of our trust, lest we should place more confidence in it than in him, therefore he makes it prove unfaithful. Outward comforts are given us as food by 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, till we get into the ark of God's unchangeableness. 'They that trust in the Lord shall be like mount Sion, which cannot be removed' (Ps. 125:1).
II. God is unchangeable in his decree. What he has decreed from eternity is unalterable. 'My counsel shall stand' (Is. 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 after, 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? There seems to be a change in his decree in Jonah 3:10: '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' (Nu. 23:19). 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 (Jonah 3:10). 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 be unchangeable, and cannot be reversed, to what purpose should we use the means? Our endeavours towards salvation cannot alter his decree.
The decree of God does not affect my endeavour; for he that 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 means to preserve my life, I will not eat and drink. God has decreed the time 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, so he that refuses to work out his salvation destroys himself. The vessels of mercy are said to be prepared unto glory (Rom. 9:23). 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 thee off from holy endeavours. It is a good saying of Dr. Preston, 'Hast thou a heart to pray to God? it is a sign no decree of wrath hath passed against thee.'
Use one: If God's decree be eternal and unchangeable, then God does not elect upon our faith foreseen, 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' (Rom. 9:11). We are not elected for holiness, but to holiness (Eph. 1:4). If we are not justified for our faith, much less are we elected for our faith; but we are not justified for it. We are said to be justified through faith as an instrument in Eph. 2:8, but not for faith as a cause; and, if not justified for faith, then much less elected. God's decree of election is eternal and unchangeable, and therefore depends not upon faith foreseen. 'As many as were ordained to eternal life, believed' (Acts 13:48). They were not elected because they believed, but they believed because they were elected.
Use two: If God's decree be 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 falls out but what he has decreed from eternity. (2) God has decreed troubles for the church's good. The troubles of God's church is like the angel's troubling the water, which made way for healing his people (John 5:4). He has decreed troubles in the church. 'His fire is in Sion, and his furnace in Jerusalem' (Is. 31:9). The wheels in a watch move cross one to another, but they all carry on the motion of the watch; so the wheels of Providence often move cross to our desires, but still they carry on God's unchangeable decree. 'Many shall be made white' (Dan. 12:10). God lets the waters of affliction be poured on his people to make them white. Therefore murmur not at God's dealings; his work goes on, nothing falls out but what he has wisely decreed from eternity; everything shall promote God's design, and fulfil his decree.
Use three: Comfort to the godly in regard of their salvation. 'The foundation of God standeth sure, having this seal, The Lord knoweth them that are his' (2 Tim. 2:19). God's counsel of election is unchangeable. Once elected for ever elected. 'I will not blot his name out of the book of life' (Rev. 3:5). The book of God's decree has no errata in it, no blottings out. Once justified, never unjustified. 'Repentance shall be hid from mine eyes' (Hos. 13:14). God never repents of his electing love. 'He loved them to the end' (John 13:1). Therefore, if thou art a believer, comfort thyself 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; and while they resist God's will they fulfil it. There is a two-fold will of God, Voluntas praecepti et decreti; 'the will of God's precept, and of his decree.' While the wicked resist the will of God's precept, they fulfil 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 fulfil the will of his permissive decree (Acts 4:28). God commands one thing, they do the contrary; to keep the Sabbath, and they profane it. While they disobey his command, they fulfil 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; 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; his decrees to permit their sin, and to punish them for their sin permitted.