"For I am the LORD, I change not; therefore ye sons of Jacob are not consumed." - Malachi 3:6
This verse right here may be one of the most important in the entirety of Scripture. Surely a whole doctrine cannot be built on this one passage, but it summarizes that which we observe again and again by our God throughout all of the Scriptures. HE is the Lord, and He changes not. And this passage gives me such great comfort and joy that words cannot describe. We have a God that does not change. We have an immutable God. And without this immutability, we would have no real faith. This is the ground of our security in Christ. We are secure in Christ, not because we do not change, but because the LORD does not change.
Our God, He declares right away that He is the Lord. Like Moses heard from the burning bush, "I am that I am" (Exodus 3:14), our Lord claims total sovereignty over everything. He declares that there is only one God, and His eternal counsel is of the Father, Son, and Holy Spirit. He is without age or time, unable to be contained to time as He created it! He sees everything at once and is everywhere at every time as He transcends all of time and space. One cannot escape His presence if they were to go to Heaven or to Hell. And when He says, "I am the Lord," those of us who are His, we cannot help but to believe and trust in Him.
And His sovereign immutabilty, summed up in these three words, "I change not," give me great comfort. I have assurance that His counsel stands forever (Psalm 33:11) and I know He has declared the end from the beginning (Isaiah 46:10). Our Lord is completely self-existent, and independent, therefore He must not change. God causes all things, but nothing can cause God. God changes all things, but nothing can change God. God declares from His heavenly abode, "I am the Lord! I CHANGE NOT!" How glorious! Everything that happens in this world does not affect Him. Sin entered into this world and has left a terrible wake in its path. But that didn't change our Lord. Nations rise and nations fall, but these things too do not change our Lord. There will be a new heaven and a new earth, but our Lord won't change. And God's elect will enter into the kingdom one day where they will be glorified forever and ever, and the reprobate will be cast into hell. And yet, our Lord still won't change.
"Ye sons of Jacob," tells me that this immutable God, He has a people who were favored from before the foundation of the world. They are His elect, predestinated by Him to be His people in eternal love (Rom 9:13-23). Jacob may have stolen Abraham's blessing to Esau, but His sons will have the Lord's inheritance. And they know that the things of this world are only temporary and that the true inheritance is Christ. They walk by faith and seek that which is to come.
And the sons of Jacob, they need not worry about being consumed. Our Lord, He changes not! The sons of Jacob, they know He does not change, and therefore He is faithful to His promises and His covenant. His redeemed people in Christ, they won't ever be consumed.
His seed also will I make to endure for ever, and his throne as the days of heaven. If his children forsake my law, and walk not in my judgments; If they break my statutes, and keep not my commandments; Then will I visit their transgression with the rod, and their iniquity with stripes. Nevertheless my lovingkindness will I not utterly take from him, nor suffer my faithfulness to fail. My covenant will I not break, nor alter the thing that is gone out of my lips. - Psalms 89:29-34
Such comfort and joy it is to know that the Lord will not break His promises. He will not. He cannot! His intentions are etched in eternity and will be brought to pass. And this God of ours, who says He won't change, has assured us through Christ that He has given all the sons of Jacob "eternal life; and they shall never perish, neither shall any man pluck them out of my hand. My Father, which gave them me, is greater than all; and no man is able to pluck them out of my Father's hand." (John 10:28-29)