The IMMUTABILITY OF GOD – defined,
The unchangeability of God. In biblical theology God is described as unchanging in His nature and in His character. This includes God’s being (essence), purposes, and promises.
Psalm 102:25–27 contrasts God’s unchanging nature with that of the created order. Numbers 23:19 and 1 Sam. 15:29 indicate that God changes neither His plans nor His actions, for these rest on His unchanging nature. James finds assurance of God’s future blessings in that there is in God “no variation or shadow cast by turning” (James 1:17 HCSB). After referring to His constant patience, long-suffering, and mercy, God concludes with a general statement of His immutability: “For I, the LORD, do not change” (Mal. 3:6 NASB).
Source: Johnson, W. (2003). Immutability of God. In C. Brand, C. Draper, A. England, S. Bond, E. R. Clendenen, & T. C. Butler (Eds.), Holman Illustrated Bible Dictionary (pp. 810–811). Nashville, TN: Holman Bible Publishers.
Since God never changes, we like to think more about His unchanging nature as expressed in endless patience, constant mercy, persistent protection, etc. We love to ponder the ‘good’ outflows from His immutability. In his Sermon #1 delivered at New Park Street Chapel, Southwark in 1855, Charles Spurgeon chose to preach on the immutability of God. After an introduction of extolling what immutability means in terms of the outflow of His other ‘positive’ attributes, Spurgeon said, “But now comes one jarring note to spoil the theme.”
To some of you God is unchanging in his threatenings. If every promise stands fast, and every oath of the covenant is fulfilled, hark thee, sinner!—mark the word—hear the death-knell of thy carnal hopes; see the funeral of thy fleshly trustings. Every threatening of God, as well as every promise shall be fulfilled. Talk of decrees! I will tell you of a decree: “He that believeth not shall be damned.” That is a decree, and a statute that can never change. Be as good as you please, be as moral as you can, be as honest as you will, walk as uprightly as you may,—there stands the unchangeable threatening: “He that believeth not shall be damned.” What sayest thou to that, moralist? Oh, thou wishest thou couldst alter it, and say, “He that does not live a holy life shall be damned.” That will be true; but it does not say so. It says, “He that believeth not.”
Here is the stone of stumbling, and the rock of offence; but you cannot alter it. You must believe or be damned, saith the Bible; and mark, that threat of God is an unchangeable as God himself. And when a thousand years of hell’s torments shall have passed away, you shall look on high, and see written in burning letters of fire, “He that believeth not shall be damned.” “But, Lord, I am damned.” Nevertheless it says “shall be” still. And when a million ages have rolled away, and you are exhausted by your pains and agonies, you shall turn up your eye and still read “SHALL BE DAMNED,” unchanged, unaltered. And when you shall have thought that eternity must have spun out its last thread—that every particle of that which we call eternity, must have run out, you shall still see it written up there, “SHALL BE DAMNED.”