"God is not like a fixed photograph. He is a Person who is constant. He is true, and faithful, and good, and righteous, and just, and holy, and He is all of this all of the time."
― Sinclair Ferguson, Behold Your God: The Weight Of Majesty
Charles Haddon Spurgeon, the great 19th century Prince of Preachers, was often called "the last Puritan." The spirit of Puritanism was certainly alive and well in his ministry.
"Consider what you owe to His immutability. Though you have changed a thousand times, He has not changed once."
― Charles Spurgeon, Morning and Evening
The fabric of which this world is made is ever passing away; like a stream of water, drops are running away and others are following after, keeping the river still full, but always changing in its elements. But God is perpetually the same. He is not composed of any substance or material, but is spirit—pure, essential, and ethereal spirit—and therefore he is immutable. He remains everlastingly the same. There are no furrows on his eternal brow. No age hath palsied him; no years have marked him with the mementoes of their flight; he sees ages pass, but with him it is ever now. He is the great I AM—the Great Unchangeable.
Mark you, his essence did not undergo a change when it became united with the manhood. When Christ in past years did gird himself with mortal clay, the essence of his divinity was not changed; flesh did not become God, nor did God become flesh by a real actual change of nature; the two were united in hypostatical union, but the Godhead was still the same. It was the same when he was a babe in the manger, as it was when he stretched the curtains of heaven; it was the same God that hung upon the cross, and whose blood flowed down in a purple river, the self-same God that holds the world upon his everlasting shoulders, and bears in his hands the keys of death and hell. He never has been changed in his essence, not even by his incarnation; he remains everlastingly, eternally, the one unchanging God, the Father of lights, with whom there is no variableness, neither the shadow of a change . . .
He is unchanged, blessed be his name, in his justice. Just and holy was he in the past; just and holy is he now. He is unchanged in his truth; he has promised, and he brings it to pass; he hath saith it, and it shall be done. He varies not in the goodness, and generosity, and benevolence of his nature. He is not become an Almighty tyrant, whereas he was once an Almighty Father; but his strong love stands like a granite rock, unmoved by the hurricanes of our iniquity.
And blessed be his dear name, he is unchanged in his love. When he first wrote the covenant, how full his heart was with affection to his people. He knew that his Son must die to ratify the articles of that agreement. He knew right well that he must rend his best beloved from his bowels, and send him down to earth to bleed and die. He did not hesitate to sign that mighty covenant; nor did he shun its fulfillment. He loves as much now as he did then, and when suns shall cease to shine, and moons to show their feeble light, he still shall love on for ever and for ever.
Take any one attribute of God, and I will write semper idem on it (always the same). Take any one thing you can say of God now, and it may be said not only in the dark past, but in the bright future it shall always remain the same: "I am Jehovah, I change not."