Just for the record: I mostly blame the Evangelicals for this mess. Their veneration of the 10 Commandments was fueled by their hate toward sinners. The 10 were useful weapons against their political opponents.
Just above, Psalm 89 is cited as a case for "God never altering His words." Specifically, this was cited in reference to God's promises.
If one is enlightened by the Spirit of Christ, they could easily deduce that Psalm 89, the whole of it, is about God's promises to David!
In 2 Samuel 7, Nathan prophesies this over David:
12 “When your days are fulfilled and you rest with your fathers, I will set up your seed after you, who will come from your body, and I will establish his kingdom. 13 He shall build a house for My name, and I will establish the throne of his kingdom forever. 14 I will be his Father, and he shall be My son. If he commits iniquity, I will chasten him with the rod of men and with the blows of the sons of men. 15 But My mercy shall not depart from him, as I took it from Saul, whom I removed from before you. 16 And your house and your kingdom shall be established forever before you. Your throne shall be established forever.” ’ ”
IF one knows Christ and is no longer blinded by the Old Testament and Moses, they would recognize that this prophesy has nothing to do with the covenant at Sinai (the one that includes the setting aside of 1/7 of one's life for God) but is in reference to Christ Jesus, the Messiah who would come.
God promised the royal line of David would persist in the earth forever. In light of the gospel, we know this was fulfilled in Jesus Christ, who is of David.
Matthew 1:1 begins thus: "The book of the genealogy of Jesus Christ, the Son of David, the Son of Abraham..."
THIS is the promise that God would not change. Indeed, He is alive in the earth, today, in us who believe.