Is theology practical? Do the deep doctrines learned in the seminary classroom really make a difference in the everyday lives of busy moms, factory workers, aging veterans, or teenagers?
Let's look at one particular doctrine and see what we find. Malachi 3:6 is the classic text teaching what theologians call the doctrine of God's immutability. “For I the LORD do not change; therefore you, O children of Jacob, are not consumed." The word immutability sure doesn't sound very practical. What difference does it actually make?
First, we see in Scripture that God is constant. He is unchanging to the point that He can be relied upon. Just as we build our lives around regular days and seasons, we can also build our lives around the constants of God's love, forgiveness, justice, holiness, and more. His unchanging nature gives us firm concrete beneath our feet in a culture of shifting sand. Notice how God tells the Israelites, in Malachi 3:6, that he does not change and, "therefore you, O children of Jacob, are not consumed." Imagine trying to please a God who was constantly changing. It would produce little more than anxiety, exasperation, and in the end, bitterness. It would be like children who have to constantly gauge the temperature of their erratic father's mood, because they never know what to expect one day to the next. This is why, in numerous places, God reminds us that he is not a man (Numbers 23:19; 1 Sam. 15:29; Hosea 11:9). Without the immutability of God, we would be consumed.
Second, the immutability of God means we will not be deceived by silly claims that God is different today than he was in Bible times, or different in the New Testament than he was in the Old. We hear this ever so often from those who are trying to strike the impossible balance of keeping one foot in the world and one foot in the church. They forget Jesus's words in Matthew 6:24, "No one can serve two masters." In an effort to justify their desire to go along with the cultural trends of the day, they will claim that God is now accepting what he used to prohibit, and frowning upon what he used to command. It can be hard for some believers to discern the error in these arguments because of the clear and biblical break between the Old Covenant and the New. However, the doctrine of God's immutability plants us firmly in the ground as part of a deep root system that keep us from being "carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes" (Eph. 4:14).
Third, the knowledge that with God "there is no variation or shadow due to change," (James 1:17) provides us an objective correction to our ever-changing feelings. There are times when it seems God has abandoned us. David felt it (Psalm 10:1; Psalm 13:1). There are times when it seems as though he is not good, or wise, or loving. Our feelings are not trustworthy guides. It would be foolish of me to trust in something so fickle. Over the course of my life, I have been surprised at how little time it takes for me to go from a mountain-top experience of exhilarating faith and confidence to the valley of the shadow of death, or at least doubt. When our feelings seem to shift as easily as the wind, the objective truth from God's Word that He does not change is "a sure and steadfast anchor for the soul" (Heb. 6:19). Martyn Lloyd-Jones, in his book Spiritual Depression, memorably wrote that most of our unhappiness in life comes from the fact that we are listening to ourselves instead of talking (or preaching) to ourselves. We let our feelings dictate the course of our day instead of taking a stand upon the external, objective truth of God's Word and preaching it to ourselves as a corrective to our feelings.
It is a critical mistake to think that theology is only for seminary students and academics—that it has little real, practical value for the everyday lives of normal people. We have only scratched the surface of the implications that flow out of this one doctrine of God's immutability. If a big word like immutability turns you off, throw it out. What's important, and intensely practical, is the concept. Deep doctrine makes a difference. If God created the world, and his fingerprints are all over it, and he created each one of us in his image, it stands to reason that theology (the study of God) is the most practical thing there is.
That will preach.