For Sunday School I am currently teaching a class on the attributes of God. This has provided me with fruitful meditations of the character of God.
For simplicity's sake, in the class I have stuck to the classic distinction in the attributes of God of incommunicable attributes and communicable ones. I realize there are some problems with this classification. Nevertheless, introductions to the attributes need to stay introductory. The incommunicable/communicable distinction is helpful for remember how God is fundamentally unlike us but also how we truly can bear the image of God.
Before I started the class I started reading this book just for my enjoyment. Having finished it, I find it incredible helpful in a key area regarding the doctrine of God and God's relationship to all his creation (full disclosure, I studied under the author in seminary). I believe it offers a helpful and correct theological grid for thinking about some of the knotty theological and exegetical problems such as how can God in Scripture be described as both changing and unchanging. How can God be beyond time and eternal but also interact with his creation.
So when it comes to God's immutability, God does not change in His nature yet because God has freely and willingly connected Himself to creation and taken on covenant attributes, God is in real relationships with his people. This involves God's response within creation without compromising His Lordship and absolute perfection over it. Thus God's aseity, immutability, eternality, infinity, etc. are all left uncompromised.
It is amazing to me how God's immutability is a doctrine that has fallen out of favor in contemporary evangelicalism whereas in Scripture it everywhere grounds the promises, reliability and trustworthiness of our great God.
It is often assumed that once we show a few passages of Scripture where God is described as changing we have defeated the doctrine without any references to clear passages where God does not change (Mal. 3:6; James 1:17; Numbers 23:19, etc.) Such shoddy handling of Scripture will not do.
We should not think that 'immutability' is a philosophical doctrine nor that the traditional approach ignored a host of Scriptures related to God's seeming 'changeability.' In fact, traditional orthodox theologians have argued that it is not inconsistent for God to be immutable and relate to his creation.
Here I find this extended quotation from Herman Bavinck to be very helpful and thought provoking:
"This immutability, however, should not be confused with monotonous sameness or rigid immobility. Scripture itself leads us in describing God in the most manifold relations to all his creatures. While immutable in himself he nevertheless, as it were, lives the life of his creatures and participates in all their changing states. Scripture necessarily speaks of God in anthropomorphic language. Yet, however anthropomorphic its language, it at the same time prohibits us from positing any change in God himself. There is change around, about, and outside of him, and there is change in people's relations to him, but there is no change in God himself. In fact, God's incomprehensible greatness and, by implication, the glory of the Christian confession are precisely that God, though immutable in himself, can call mutable creatures into being. Though eternal in himself, God can nevertheless enter into time and, though immeasurable in himself, he can fill every cubic inch of space with his presence. In other words, though he himself is absolute being, God can give to transient beings a distinct existence their own. In God's eternity there exists not a moment of time; in his immensity there is not a speck of space; in his being there is no sign of becoming. Conversely, it is God who posits the creature, eternity which posits time, immensity which posits space, being which posits becoming, immutability which posits change. There is nothing intermediate between these two classes: a deep chasm separates God's being from that of all creatures. It is a mark of God's greatness that he can condescend to the level of his creatures and that, though transcendent, he can dwell immanently in all created beings. Without losing himself, God can give himself, and, while absolutely maintaining his immutability, he can enter into infinite number of relations to his creatures." (Reformed Dogmatics, Vol 2 pp.158-59.)
But there is a deep practical import to the doctrine of God's immutability: God's promises are reliable because the nature, purposes and plans of God do not change. Because He is an immovable and eternal Rock, I can be find a perfect anchor for my soul. We should not think that God is approachable and relational because He is mutable (as if that were a good thing), we should assume that the covenant and relational God is dependable and reliable in His covenant relationships because He is fundamentally immutable.