What are some arguments that support the doctrine of divine simplicity?

from the old testament

• “Divine simplicity” means that God is not part love and part mercy and part holy, but rather entirely love, entirely merciful, and entirely holy. “Simplicity,” then, refers to a lack of parts. A key verse supporting this doctrine is Deuteronomy 6:4, which says, “Hear, O Israel: The LORD our God, the LORD is one.” While this instance of oneness applies specifically to the doctrine of the Trinity—that God exists in three Persons all sharing the single divine essence—it also implies that God is defined by His oneness.
• In addition to passages which talk about God’s oneness, divine simplicity is the logical conclusion on the basis of His attributes. What follows are examples of how God’s core nature—eternal, unchanging, and infinite—support this doctrine.
• For example, evidence for God’s simplicity is found in His eternality. Moses asked God to give His name, and He said, “I AM WHO I AM” (Exodus 3:14). That was a declaration of eternality. That means that there was never a time when He did not exist. For something to be “composed,” that is, to be made from a combination of parts, then 1) those parts must exist independently of the composed thing, and 2) they must somehow be put together at a specific point in time. However, God's self-existent nature, as shown in His name, conveys that God was not “put together” at some point. Rather, He has always been and is a pure being without division or dependency.
• God’s unchanging nature is also evidence of His simplicity. If God was, for example, only part holiness then it would be possible for His holiness to rise or fall over time. Yet God said, “For I the LORD do not change” (Malachi 3:6a). His unchanging nature affirms that there are no pieces to shift around or introduce internal instability. That is because He is One.
• God is also infinite. “Can you find out the deep things of God? Can you find out the limit of the Almighty? It is higher than heaven—what can you do? Deeper than Sheol—what can you know?” (Job 11:7–8). Being infinite means that He, and who He is, has no bounds. Logically, an infinite being cannot be made up of parts. If He was made of individual parts, then their sum total, no matter how big each part was, would always add up to less than infinite.

from the new testament

• Jesus said that “God is spirit” (John 4:24a). His point was that God is not confined to a particular location but is everywhere at once (John 4:20–21). This speaks both of His infinitude and the fact that He is not bound by the limitations of physical or metaphysical (spiritual) composition.
• In addition to being spirit, we also learn that “God is light” (1 John 1:5), “God is love” (1 John 4:8), and “God is a consuming fire” (Hebrews 12:29). These “is” statements are statements of being. They are not what He does, but who He is. Only the doctrine of divine simplicity makes sense of how God can be all of these at the same time.
• In addition to His simplicity, as implied by the state-of-being verses, Jesus, the Son of God, affirmed, “I and the Father are one” (John 10:30). The Jews understood that He was claiming to be God and “picked up stones again to stone Him” (John 10:31). While Jesus’s statement is primarily about unity between the Father and Son, it reflects the greater truth of the simplicity within the divine nature. There is no internal contradiction and no separation of will or purpose.
• As stated in the Old Testament section, God’s unchanging nature points to a God who is not made up of movable parts. James noted that God is the “Father of lights, with whom there is no variation or shifting shadow” (James 1:17 [NASB]). God does not “shift” because He is not composed of parts that can move around.
• Hebrews 13:8 declares that “Jesus Christ is the same yesterday and today and forever.” The unchanging character of Christ further evidences God’s unchanging nature and, thus, supports divine simplicity.
• Because God is the source of all things, Paul can affirm, “For from him and through him and to him are all things” (Romans 11:36). God’s role as the source and goal of all things reflects His self-sufficiency and internal completeness.

implications for today

It is impossible for us to understand divine simplicity because we don’t know what it means to be everything at once. This is one of the doctrines in Scripture that we cannot support from experience. Instead, we must allow the verses, and the logical conclusions we derive from them, to speak for themselves. The simplicity of God may sound like an abstract, useless doctrine. However, it provides deep, practical comfort and theological clarity. It reminds us that God is not complex in the way that we are. He does not struggle with competing desires, fluctuating emotions, or shifting priorities. When we pray to God, we are not approaching One who is part merciful, part just, and part holy; we are coming to a God who is fully and perfectly all of these things at once. This means that we are not trying to appeal to His “good side,” as if He might suddenly turn and destroy us.

This also means we can fully trust His Word. Because He is not made of parts, He cannot be divided against Himself. His justice will never override His goodness. His love will never cancel out His holiness. Every promise, warning, and act of providence flows from a perfectly unified nature.

Moreover, divine simplicity guards God’s independence. He is not assembled, improved, or evolving. He is not becoming anything—He simply is. We worship a God who needs nothing, lacks nothing, and depends on nothing. That means He will never change, never fade, and never be diminished. He is a sure foundation for faith, a steady anchor in a world of complexity and contradiction.