Earthly leaders and political authorities make promises all the time. It's how they sway voters and glean public support for their ideas. Some of the promises are actually carried out. Many others are not. But, leaders are no different than anyone else. They're sinners too. They will die and their promises will perish with them. Then, somebody else comes along with new promises and the phenomenon repeats itself.
If God's promises were limited in the same way ours are He wouldn't be a god worth worshipping. God must keep His promises to us. Otherwise, if His promises changed from day to day or week to week, He wouldn't be trustworthy. When God says, "I am the Lord, I do not change," He proves these words are true by keeping His promise day after day, week after week, generation after generation. His promise to not change will persist because, as He says, He is the same yesterday, today, and forever.
Faithlessness is the primary trait of every person. Faithfulness is the defining attribute of our God. This is demonstrated for us by the psalmist's words when he writes: "He is the Lord our God. His judgments are in all the earth. He remembers His promise forever. The Word which He commanded, for a thousand generations." (Psalm 105:7-8)
All our lives we wade through broken promises. Deceit abounds wherever we turn. We could try to escape but where could we go to spare ourselves the pain of broken promises? We could run away to a cabin in the mountains or a hut in the remotest jungle, but it wouldn't matter. Wherever we go we carry our sinful condition with us. Even if we do flee from others we will end up breaking our promises to ourselves and deceiving ourselves about it. Only when we stand where God has located Himself for us do we find an imperishable promise.
This has been shown to us numerous times in Scripture with God's chosen people. Abraham, for example, the father of believers, was given a promise. He would be the father of a great nation, more numerous than the stars in the sky or grains of sand on the seashore. Abraham received God's promise, then each succeeding generation received the same promise.
God's promise which is for us today has not changed either. Despite all the broken promises that pain us, our Savior, who paid the penalty for all our sins on the cross, promises, "it is the LORD your God who goes with you. He will not leave you or forsake you." (Deuteronomy 31:6) He did not abandon Israel in the wilderness or the world on the cross, therefore we trust that He will not abandon us today.
We call upon the name of Jesus, the name of our God and Lord because He proves Himself to be trustworthy to us. His bloody suffering and death for us, and resurrection, forgives sin, renews our life, and gives us eternal salvation. Likewise, in our vocations, He works in and through us to produce fruits of love for the benefit of our neighbors, just as He's promised to do.
In this way, every day, amid failed promises and deceit, we can be assured that our God will never fail us whether we are at worship or at work. His mercies will be new every morning. Every day a Sabbath's rest for us in the peace of the Lord.
His promise to be our God and Lord buries the broken promises and gives us grace and truth in their place. This is our constant comfort and encouragement. In a deceitful world deformed by broken promises, Jesus proves Himself trustworthy by never giving up on His promise to be our God, our Lord, and our Savior.