This psalm ends the same way it began: “Oh give thanks to the Lord, for He is good; for His steadfast love endures forever” (v29).
At the end of all that Psalm 118 has said about what God has done, the psalmist reminds himself (and us) that everything is grounded in God’s covenant love.
How do we know that the Lord still saves and that He still protects His people? We know because “His steadfast love endures forever.” He will not break His covenant. He brought you into His covenant through the blood of His Son – and He will not and cannot change.
So we can say with confidence: “You are my God” (v28).
And we can say, even though we might have many troubles: “I will give thanks to You.” (v28).
I can worship, I can trust Him, I can be sure that He is my God because He is unchanging and His covenant love endures forever.
That is the solid rock on which every believer stands.