The Christian God is not unchanging. He is not a God that looks at the world with disinterest, like the God of Deism. He is affected by what happens to us, His creatures. God "does care what happens to men and women - He is concerned about the changes upon earth. he alters His behaviour in accordance with the changes in men." (pg. 268) To say that God changes at the beginning sounds like heresy at best and blasphemy at worst. But the opposite is true. If God did not change, at least in behaviour, he would be a cruel God that was not Loving or Merciful. God, to be loving, has to change.
"God 'reacts', He changes. God says: "I will not cause my countenance to fall upon you." He "hideth His Face", H withdraws Himself- and again: He draws near, He discloses Himself, He "makes His face to shine upon thee"." (pg. 268) In this quote, Brunner reminds us that the Divine Activities are full of actions that constitute change. God is not a passive God, but an active God, reacting and changing.
This doctrine is easy to grasp once getting over the initial shock. However, it entails a statement that is much more troubling. "God repented Himself". (Amos 7:3, Jer. 42:10, I Sam 15:11) "Behind this expression 'God repented Himself', there lies, in point of fact, nothing less than the fundamental Biblical idea of the relation between God and the world." (pg. 269) This fundamental idea is that God has willed the independence of those that He created, and then enters into the world His creatures have created. By entering the world not created by Him, He limits Himself and behaves according "to the behaviour of man." (pg. 269) This idea might raise hostility, if we are still operating under the understanding that God is potestas absoluta, the Absolute Power that cannot change and cannot be limited. Yet, in His Love, God limits Himself, which causes Him, in His Mercy to repent of Himself.
Brunner continues to say, "If the expression 'God repented Himself' arouses hostility, then on the other hand, the assurance that God hears prayer shows the significance of this hostility very clearly."(pg. 269) We want a God that has the absolute power to change everything when we petition in Him in prayer, yet at the same time, we do not want a God that can change. This is not a paradox, but a blatant contradiction. For both the God who hears prayer and the God who repents is the God that "is interested in what happens upon earth." (pg. 269)