I argue that holding to divine immutability is vitally important to a proper conception of God. Without a proper conception of God, we cannot do well in representing Him to the world. This negatively affects our evangelism and discipleship. If the foundation of our faith rests upon that which is changeable, then it does not rest on what should be understood as 'God'. Our faith will eventually crack under the pressure of time. Many errors in doctrine develop from a mistaken concept of God. The LDS belief system is a case study in this regard, where God (YHWH) is a literal father of humanity and is/was seen in physical form (see https://www.lds.org/scriptures/bd/god). Change is a primary predication of physical, spatially-extended things. One who understands God as immutable would have to reject the LDS conception of God. They might be talking about something else, but certainly not the Creator and Sustainer of the universe.
Divine immutability is challenged on both biblical and philosophical grounds. Many passages in the Bible describe God as changing (Gen. 6:6, Ex. 4:14, Amos 7:3, etc.). And it seems that if God cannot change, then we must accept a rigid determinism, salvation would be non-sensical, God could not be all-loving, and many other problems of coherence in divine attributes. Yet, the Bible also says that God does not change (Malachi 3:6, Psalm 90:2). The classical theistic tradition has defended divine immutability from a robust metaphysical standpoint, starting with objects of everyday experience, reasoning to God, then progressing from God's pure actuality, simplicity, aseity, and necessity. Natural theology provides a means of successfully exegeting biblical passages that refer to God and His activity in anthropomorphic ways.
I think much of the opposition to divine immutability comes from a deep desire to make God like us. This might spring from either good or bad motivation. A good motivation would be genuinely wanting to know God more intimately, thinking that we can only relate to something that is just like we are. A bad motivation would be wanton idolatry, shrinking God so that we can put Him alongside (or behind) the other objects of our thought. In any event, the result is the erroneous reduction of God to that which we can fully comprehend. We must avoid this at all costs.
Think of what it would mean for God to change. For the sake of simplicity, we might understand change via consulting the Aristotelian categories (sans substance). Here is a convenient breakdown from Dr. Taylor Marshall:
- Quantity (“how much”). This is the extension of an object and may be either discrete or continuous. Further, its parts may or may not have relative positions to each other.
- Quality (“of what kind or quality”). This is a determination which characterizes the nature of an object.
- Relation (“toward something”). This is the way in which one object may be related to another.
- Place (“where”). Position in relation to the surrounding environment.
- Time (“when”). Position in relation to the course of events.
- Position (“to lie”). The examples Aristotle gives indicate that he meant a condition of rest resulting from an action: ‘Lying’, ‘sitting’.
- State or habitus (to have”). The examples Aristotle gives indicate that he meant a condition of rest resulting from an affection (i.e. being acted on): ‘shod’, ‘armed’. The term is, however, frequently taken to mean the determination arising from the physical accouterments of an object: one’s shoes, one’s arms, etc. Traditionally, this category is also called a habitus (from Latin habere, “to have”).
- Action (“to make” or “to do”). The production of change in some other object.
- Affection ( “to suffer” or “to undergo”).
Yet, for God to change in any of the categorical aspects would mean that God would have the potential to undergo such change. If God has any potential whatsoever, He would not be God. Potential to change in God would mean that there is something beyond or outside of God that could fulfill or actualize this potential. God would then not exist a se (in Himself). Further, we would be forced to seek a first cause in any hierarchically ordered series (such as any contingent thing existing at any moment).
I am not pretending these, the principles on which divine immutability on classical theism are developed, are not contentious metaphysical notions. They certainly are. However, we are forced to ask about the implications of any given view of God. What happens if we deny immutability? Some would take this as a "bogey-man" question. This rejoinder is that we do not need to necessarily think anything bad would result if God could change. Again, maybe He can change but just wills not to. Such a rebuttal misses the point. What is it about God by which one predicates the potential to change? It is just this thing, whatever it might be, that the classical theist objects to regarding conception of God. Further, how is it that we arrive at immutability in the first place? Since we find disparate notions in Scripture in this regard, God has given us the capacity for natural theology to buttress our understanding. What is the natural theological method that leads one to think God can change? Should we think such a method is sound and systematically coherent? If not, then why should we trust the outputs?
When we think about God, we must humble ourselves. This can very difficult for us as prideful and puffed up people. I think that the proper humility demands our acquiescence to the divine mystery. God, in His Essence, is not comprehensively knowable by us. This is ok! It is good for us to grow in our knowledge of Him as we eternally enjoy Him. We will never, we can never, plumb the depths of God.