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Divine Simplicity and Trinitarian Action

A Simple, Triune Divine Unity

One crucial aspect of storytelling is the concept of a “through line.” A through line connects themes and story structure throughout the story. In The Lord of The Rings, Frodo’s journey to destroy the Ring of Power in the fires of Mt. Doom serves to connect the many themes and subplots throughout the trilogy. Even when major events happen, like the siege of Helm’s Deep or the Ent’s attack on Isengard, they happen in the context of Frodo’s sacrificial mission from the Shire to Mordor.

Through lines exist in theology, too. Certain doctrines and concepts guide the theologian as he or she contemplates God and all things in relation to God. One such through line is the concept of God’s unity. Classically, trinitarianism follows the “through line” of divine unity from God’s being all the way to God’s actions in the world. In this classical view, the divine persons are not merely cooperating in harmony with one another but share in the same divine nature and perform numerically the same action in the world. Classical trinitarianism follows the thread that begins with the affirmation of a simple divine essence and concludes with the affirmation that every economic action of the Trinity is inseparable.

Certain doctrines and concepts guide the theologian as he or she contemplates God and all things in relation to God. Click To Tweet In post-Enlightenment theology, it became popular to venture from this through line and to view the relationship of divine persons similarly to the relationship of human persons. The Father, Son, and Spirit are in a divine society with one another, and each act separately from one another (though in complete harmony and cooperation). The unity of the Godhead is more akin to a unity of purpose rather than a unity of being and action.

I am convinced that we must not lose the plot. If we follow the through line that begins with God’s simplicity, then we will arrive at the inseparable operations of the Trinity in the economy.

Unity and God’s Essence

God’s unity and singularity leads to the confession that God is metaphysically simple. “We all believe in our hearts and confess with our mouths,” states the Belgic Confession:

“that there is a single

and simple

spiritual being,

whom we call God.”

The doctrine of divine simplicity answers the question, “What is God made of?” Negatively, the doctrine answers, “God is not made of anything.” A litany of implications follows this claim. Some of simplicity’s more modest claims are readily apparent from Scripture. God could not be a material composition because God is spirit (Jn 4:24a). God is not a physical being but a “spiritual being,” as the Belgic Confession states. God is not composed of matter and cannot be broken down into any material parts. More controversial claims, however, necessarily follow from this basic claim. According to the classical doctrine of God, God is not a composition of attributes and essence. What we call God’s attributes, like His omnipotence, His love, and His eternality, are not separate from or ontologically behind the divine essence. We, using human language, provide conceptual glosses on the divine essence. Like white light that bursts into a rainbow after passing through a prism, the divine essence “passes through” revelation and we perceive the rainbow of God’s attributes (which are just the divine essence). God’s unity and singularity leads to the confession that God is metaphysically simple. Click To Tweet

Another implication of divine simplicity is that God’s essence is His existence. God’s existence is of a totally different kind than that of creatures. Creatures receive their existence from God in whom we “live and move and have our being” (Acts 17:28). Additionally, you and I exist but not by necessity – we could have possibly not existed. Neither of these truths of existence applies to God. God does not receive His existence from anything besides His own essence. Further, God’s non-existence is an impossibility. God exists by His own nature.

So, why is it so important for classical theism to affirm divine simplicity? Is such a claim of divine unity necessary for a robust doctrine of God? Undoubtedly, yes. To affirm that God is simple is to affirm that God is the sufficient reason for His own existence, essence, and attributes and that He does not possess His perfections by relation to anything or anyone other than Himself. Thus, the denial of simplicity necessitates a denial of God’s aseity.

Stephen Charnock (1628-1680) summarizes this argument:

God is the most simple being; for that which is first in nature, having nothing beyond it, cannot by any means be thought to be compounded; for whatsoever is so, depends upon the parts whereof it is compounded, and so is not the first being: now God being infinitely simple, that nothing in himself which is not himself, and therefore cannot will any change in himself, he being his own essence and existence.[1]

If God were composed of parts – physical or metaphysical – He would rely on those parts for His existence, and He would depend on whoever or whatever composed those parts. Anything composed of matter is, in theory, subject to change and ontological determination. God, however, is the giver of being. He is Creator of all that is. If God received change from another, He would depend upon others to some extent. There is no “form” that stands behind God. Rather, God’s essence is His “form.” God, unlike the physical objects He created, is not a hylemorphic being with the potency to change. Likewise, God is not a “kind of thing” or an instance of some genus of God. God is utterly unique, such that “He must be His own Godhead, His own Life, and whatever else is thus predicated of Him.”[2] The denial of simplicity necessitates a denial of God’s aseity. Click To Tweet

Unity and the Trinity

The through line of God’s unity continues from God’s essence to the divine persons. The simplicity of the divine essence means that the divine persons are not something other than the divine essence. It is not as if there is a composition of substance (the divine essence) and accidents (the divine persons). Classical trinitarianism insists the divine persons are the divine essence in particular “modes of being.” The Father is the divine essence unbegotten, the Son is the divine essence begotten from the Father, the Spirit is the divine essence proceeding from the Father and Son. The Father is totally God, the Son is totally God, the Spirit is totally God, and God is totally the triune persons.

If the divine persons are fully God (and are identical to the divine nature in particular “modes of subsistence”), then anything that is true of the divine essence can be said to equally describe the Father, the Son, and the Holy Spirit. Two examples include the divine will and divine power. Classical trinitarianism asserts both the simplicity of the divine essence and the equal subsistence of each person in the divine essence, thus concluding that the divine persons must share one divine will. Here, an important clarification is needed. “Will” does not simply describe the purpose or intention of God but His volitional capacity to act. So, in discussing the “divine will,” trinitarian theologians are speaking of the faculty of the will, not of any particular act of willing. In other words, the will is to be distinguished from particular acts of the will. When the tradition speaks of the divine persons as sharing a “common will,” it is not simply making a claim about their agreement in purpose and intention. According to classical trinitarianism – the consensus of the Christian Church from the fourth century to the Enlightenment – the divine will is a property or attribute of the divine essence rather than not a function of the divine persons. The Father is the divine essence unbegotten, the Son is the divine essence begotten from the Father, the Spirit is the divine essence proceeding from the Father and Son. Click To Tweet

Similarly, “power” is also a property of nature. A being’s “power” is their “capacity” to perform certain actions. Pro-Nicene theologians confessed a certain “class” of actions that could only be performed by God. Creation was a crucial demonstration of this notion. The book of Isaiah frequently claims creation demonstrates God’s ontological uniqueness (Isa. 37:16; 40:25–26), for God alone created (44:24). In the New Testament, creation is revealed to be an act of God through the Word (John 1:3). It is an act by, through, and for the Son (Col. 1:16). Similarly, Old Testament passages, when read in light of the personhood of the Spirit, claims that God creates by the Spirit (Job 26:13; Ps. 33:6). If each divine person is ascribed the action of creation, then each divine person possesses the “affective capacity” to perform certain actions, denoting a certain kind of nature.

In other words, Christians ought not to think of the divine persons as a community of divine beings who equally (or unequally) partake in godhood and whose unity is merely a unity of will instead of a unity of being. God is not like the mythological guardian of Hades, Cerberus, whose three heads held three centers of consciousness that could disagree with one another.[3] Instead, simplicity compels us to confess that the divine essence just is the action of the Father begetting the Son and the Father and the Son spirating the Spirit. As such, each divine person shares a common will (volitional capacity to act) and acts via a common power (affective capacity to act).

Unity and Trinitarian Action

The through line of divine unity via simplicity carries us all the way from God in Himself to God’s actions in the world. Classical trinitarianism affirms the patristic slogan, opera trinitatis ad extra indivisia sunt, or, “the external operations of the Trinity are undivided.” According to the Nicene understanding of the Trinity, any action of one divine person is the action of each divine person. The inseparable work of the Trinity is inseparable from the inseparable unity of the Triune Persons. According to classical trinitarianism, the divine will is a property or attribute of the divine essence rather than not a function of the divine persons. Click To Tweet

This unity of action, flowing from the unity of being, is more than merely a unity of “action type.” Some social trinitarian constructions view divine operations as cooperation between three persons with separate wills and powers. In other words, all three persons work the same kind of action but not the same specific action. All three persons might, therefore, participate in the act of creation but not the same specific actions. The unity is merely a unity of cooperation.

Scripture, on the other hand, insists the indivisibility of the operations runs all the way down to specific action tokens and not merely action types. Throughout the gospel accounts, Jesus identifies His actions as the very actions of the Father and Spirit (Jn 5:17, 10:32; Mk 3:22-30). Paul often identifies the Spirit with the Father, especially in the distribution of spiritual gifts and empowerment (Gal 2:8; 3:5; Eph 1:11; Phil 2:13). Scripture pressures us to identify the unity of the Persons, not merely as a cooperation of actions, but as a unity of being revealed to us in the unity of their actions.

The doctrine of divine simplicity supports the doctrine of inseparable operations because essence determines actions. If the divine persons equally subsist as the divine essence in particular relations (unbegotten, begotten, and spirated), then the persons must act in a certain way. Since the persons have a singular volitional capacity to act (will) and affective capacity to act (power), this leads to the conclusion that the persons of the Trinity inseparably perform one and the same action in the world.


This account of the Trinity differs from social models of the Trinity that arose in the 19th and 20th centuries. It is an account that follows the revelation of the Trinity presented in Scripture: Beginning with the absolute singularity of God in Shema and concluding with the affirmation that the Father, Son, and Spirit are this One God.


[1] Steven Charnock, The Existence and Attributes of God (Grand Rapids: Baker Books, 1996), 459.

[2] Thomas Aquinas, ST, I, q. 3, a. 3.

[3] J. P. Moreland and William Lane Craig, Philosophical Foundations for a Christian Worldview, 2nd Edition (Downers Grove: IVP Academic, 2017), 600.

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Jake Rainwater

Jake Rainwater (PhD, MBTS) is the Assistant Registrar and an adjunct instructor at Midwestern Baptist Theological Seminary. His Ph.D. research focused on the covenant of redemption, divine simplicity, and trinitarian action. He is a member of Emmaus Church in North Kansas City, serving in various lay positions. He is married to his high school sweetheart, and they have two young children that terrorize their Great Dane, Scotland.

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