One of the tragedies of the modern period is the loss of classical theism. The principles of classical theism provide a rigorous defense and explanation of the Christian view of God – a view which is under attack today. It is not “cool” to hold traditional beliefs in a God who is unchanging, independent, and simple. Many people, even prominent evangelical thinkers, question the doctrines of classical theism. For instance, both Dr. William Lane Craig and Dr. James White criticize the classical notion of divine simplicity.1
In this article, I intend to introduce you to the theology of classical theism. This is a follow-up on previous articles, as classical theism relies heavily on philosophical inferences from observations of the natural world. The principles of classical theism provide a rigorous defense and explanation for the Christian view of God. These principles serve as a preamble to our discussions about faith, and they provide powerful support for the traditional, orthodox view of God which is under intense scrutiny today.
Once again, I will enlist the aid of one of history’s brightest theologians: Thomas Aquinas. Beginning with his arguments for God’s existence, Saint Thomas argues for several divine attributes that are crucial for our theology. Today I will highlight five of those attributes. This list leaves much unsaid, but my hope is to whet your appetite to learn about these attributes (and more aspects of classical theism) in your own time.
Aquinas on God’s existence and nature
Everything begins with Aquinas’ arguments for God’s existence. He proposes five ways to demonstrate that God exists, the first of which is an argument from motion. Briefly, here is his case:
- Things change. We observe change all around us.
- Everything that changes is moved by something else. Change requires an external cause.
- There cannot be an infinite regress of external movers.
- Therefore, there must be a first mover: God.
From this conclusion that God is the first cause of motion, Aquinas moves on to show what can we learn about this first cause. What characteristics logically follow from the fact that God is the first cause? 2
- God is Immutable
This means God cannot be changed or moved. If God was movable, he would need to be moved by something else. And if he was moved by something else, he would not be the first cause of motion. Therefore, in the words of Aquinas, “God is altogether immovable.”3
- God is Eternal
Everything that begins to exist or ceases to exist undergoes movement or change. But God is immovable, as shown above. Therefore, he never begins or ceases to exist. He is eternal.4
- God is Self-Existent
Since God is the first cause of all things, he does not have a cause of his own existence.5 He is utterly independent and self-sufficient. This is the attribute of divine aseity.
- God is Simple
This means God is not composed of any parts. If something is composed of parts, those parts existed prior to and are more fundamental than the whole. But nothing existed prior to God, as he is the first cause. Therefore, God is not composed in any way.6
- God is Perfect
If God were not perfect, he would have some fault or deficiency. If God had a deficiency, he would depend on something external to supply that need. But God is utterly independent and self-sufficient, as shown above. Therefore, he is perfect, lacking in nothing.
After Aquinas discusses what we can know about God through natural reasoning, he reminds us that many non-Christian thinkers have reached similar conclusions about the divine nature. He writes, ”many pagan philosophers also acutely considered the things about God related in previous chapters.” (35) Yet these pagan thinkers only reached those conclusions about God after “long and diligent inquiry.” (35) Such knowledge is not enough for salvation. There are “things about which the Christian faith instructs us beyond human understanding.” Chiefly, natural reasoning cannot deduce that God is Father, Son, and Spirit. Our knowledge of the Trinity arises from the revelation of Scripture.
Why does this matter?
Why is it beneficial to know the reasoning that shows God’s unchangeableness, eternity, independence, simplicity, and perfection? What value does Aquinas’ philosophy have for us?Allow me to offer a couple of reasons.
First, the attributes discussed above can benefit us by providing a preamble to the faith we seek to spread. The Apostle’s creed begins by professing belief “in one God, the Father almighty, maker of heaven and earth.”All five of the above attributes (immutability, eternality, aseity, simplicity, and perfection) expound on God’s identity as the one, almighty Creator. When Paul preached to the men of Athens, he began with God’s identity as the infinite and independent Creator. “The God who made the world and everything in it, being Lord of heaven and earth, does not live in temples made by man, nor is he served by human hands, as though he needed anything, since he himself gives to all mankind life and breath and everything.” (Acts 17:24-25) Now, Paul did not stop with God’s power and independence. He shared the gospel and called his audience to repent. But his doctrine of God served as a necessary preamble to his gospel presentation. We should reflect on these doctrines of God, so we can deepen our understanding of the foundations of Christianity, and share that understanding more effectively through evangelism.
Second, when we know both the biblical and philosophical underpinnings for our beliefs about God, we have a stronger anchor for our faith. When others offer a different view of God, such as when Greg Boyd claims that God can change, how do we address it? We have our verses, and Greg Boyd has his. When we understand how God reveals himself in nature, we add ballast to our faith. Philosophy aids our theology. There is wisdom in appealing to history’s most brilliant minds while still holding Scripture in the highest regard. Bad theology is accompanied by bad theology, and we should refute it with the same.
Your faith need not unravel if someone brings up several verses that seem to describe God as changing his mind or possessing a physical body. You need not worry that God is not as powerful or good as he claims to be. God gave us Scripture as well as the capacity to reason well. We can know God as he intended to reveal himself: through the natural world and natural reasoning, as well as the supernaturally-inspired divine Word. Through these means, we can have confidence that our faith rests on a Rock who is perfect, faithful, and just (Deuteronomy 32:4).
- https://www.reasonablefaith.org/writings/question-answer/divine-simplicity-2021,
https://www.youtube.com/watch?v=YKCLbxqWnEo&t=1s ↩︎ - Thomas Aquinas, Compendium of Theology, 3 ↩︎
- Thomas Aquinas, Compendium of Theology, 4 ↩︎
- Thomas Aquinas, Compendium of Theology, 5 ↩︎
- Thomas Aquinas, Compendium of Theology, 6 ↩︎
- Thomas Aquinas, Compendium of Theology, 9 ↩︎
