In view of 1 Samuel 15:35 which says that the Lord regretted that He had made Saul king, a Presbyterian brother asks: “Does God change his plans for us, depending on our responses, or does God’s sovereignty mean that He ‘did unchangeably ordain whatsoever comes to pass’ (The Westminster Confession of Faith)?”
I take the passage you quote at face value. The Bible frequently represents God as changing his mind about earthly affairs, depending on the actions and reactions of people. One thinks of Abraham’s intercession for Sodom (Gen. 18:20-33), God’s saving and then destroying the Israelites in the wilderness (Num. 14:1-35), his choice and later rejection of Eli’s priestly house (1 Sam. 2:27-36), the Ninevites’ repentance and deliverance (Jonah 3), and similar references in the prophets (Ezek. 18:21-32).
Someone might say that God had an ultimate sovereign plan in each of these cases which represented the final picture, and that the first-announced intention was merely contingent in his mind although declared as if it were absolute. The Westminster Confession seems to allow for that possibility in adding that “the liberty or contingency of second causes” is not “taken away, but rather established.” But it also denies that God “decreed anything . . . as that which would come to pass upon such conditions.” The fact that I cannot reconcile those statements might only mean that my mind is tiny in comparison to the Westminster authors. It is also possible that in their zeal for God’s sovereignty those worthy theologians simply overstated one biblical truth to the neglect of another.
However we understand God’s ordination of the details of daily life on earth, we may be confident as believers that our salvation in Christ remains on solid ground. Scripture specifically assures us that the self-offering of Jesus our high priest has set us right with God, and that Jesus will forever mediate that atonement and salvation for all his people. On that point, God promises that he “will not change his mind” (Heb. 7:21-22, 25; Ps. 110:4; Heb. 6:16-20).