"But the Lord shall endure for ever: He hath prepared His throne for judgment" (Psalm 9:7).
This world will eventually pass away. The law of entropy assures us, in fact, that everything decays and dies. Atheistic scientists have even calculated that the very protons of which matter is composed will eventually disintegrate. And the Bible itself also tells us that the present Earth and heaven "shall wax old as doth a garment" and "shall perish" (Hebrews 1:11).
But God Himself is eternal! As our text confirms (and many other texts agree), "the Lord shall endure for ever." And that is not all! His glory will remain! "The glory of the Lord shall endure for ever: the Lord shall rejoice in His works" (Psalm 104:31).
And His great name will never change. "His name shall endure for ever: His name shall be continued as long as the sun: and men shall be blessed in Him" (Psalm 72:17). That means too that His righteousness will never change. "His righteousness endureth for ever" (Psalm 112:3).
Then also "His mercy endureth for ever." All 26 verses of Psalm 136 end with this wonderful assurance, and the same promise occurs 16 other times as well. If God's perfect righteousness will last forever, then also His great mercy must endure forever, and we shall continue to thank Him for His everlasting mercy in all the ages to come.
Next, God's Word will endure. "For ever, O Lord, thy word is settled in heaven" (Psalm 119:89). "But the word of the Lord endureth for ever. And this is the word which by the gospel is preached unto you" (I Peter 1:25).
Finally, because God is forever, we also shall live forever. "His seed shall endure for ever" (Psalm 89:36). "The world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever" (I John 2:17). HMM