Note: The following is taken from chapter 20 of the upcoming book The Absurdity of Unbelief, which may be pre-ordered here.
It is true that God is a simple being that is not composed of non-divine parts. For instance, if the attribute of power was not essential to God’s nature, then power would cease to be divine, which would cause God to be dependent on something outside of Himself for Him to be omnipotent. Because God cannot be dependent on anything other than Himself, He cannot be composed of any non-divine parts.
God’s simplicity implies that His nature consists of His attributes, and His attributes do not exist independently or outside of God. This also implies that each attribute is inseparably necessary and essential to the other attributes of God. That is, it is logically impossible to separate or remove any of the attributes of God without destroying God in the process. Each of God’s attributes properly describe each of the other attributes of God in the same way that they each describe God. Because God is love, God’s love is sovereign, eternal, and omniscient in the same way that God is sovereign, eternal, and omniscient. Finally, this implies that each and every attribute of God (in-and-of-itself) consists of the fullness of God. In this way, God is a simple being without non-divine parts. He is what He is.
God being simple, however, does not mean that He is without any formal differentiations within Himself.  Saying that God cannot be a collection of non-divine parts (i.e., parts that are not in-and-of-themselves fully God) is not the same as saying that God cannot subsists in different divine persons that are (in-and-of-themselves) fully God (i.e., autotheos).
For instance, because each of the three persons of the Godhead are (in-and-of-themselves) fully God, formal differentiations and relations are inherent and necessary in God. According to Oliphint, “These personal distinctions and relations are all identical with him; they are not ‘added’ to him from the ‘outside.’” In other words, the differentiations within God are essential to who God is.
Formal differentiations within the Trinity imply that God is not only able to distinguish between things outside Himself but that He is able to distinguish between different things inside Himself. For example, God the Father knows that He is neither the Son nor the Spirit, the Son knows that He is neither the Father nor the Spirit, and the Spirit knows that He is neither the Father nor the Son.
Moreover, the formal differentiations between the three persons of the Trinity are not merely conceptual distinctions within the mind of God; rather, they are an essential part of His ontology. Jay Wesley Richards, a senior fellow at the Discovery Institute, reminds us that “the Father and the Son could not change places.” Richards went on to elucidate:
There is some fact about the Father that makes him the Father and not the Son, and some fact about the Son that makes him the Son and not the Father, even if we can refer to these separate facts by means of single asymmetrical relation. Moreover, the relation of the Father to the Son is not the same as the relation of the Father to the Spirit. Therefore, if one wishes to retain the trinitarian distinction, one must deny that every essential divine property or relation is strongly equivalent.
Consequently, there can be and there are essential and eternal distinctions within the very being of God. This implies that God’s simplicity must be understood in light of the diversity found in the Trinity. Specifically, God’s simplicity does not cancel out His multiplicity. “To avoid the blank identity of pantheism,” Van Til claimed, “we must insist on an identity that is exhaustively correlative to the differentiations within the Godhead.”
If there were no formal differentiations within God, as with Allah, the Aristotelian Unmoved Mover, and the god behind pantheism, then God would become pure unity without any diversity at all. In fact, as pointed out in the last chapter, non-trinitarian theism, in all of its forms, is reducible to monistic pantheism.
The Solution for Divine Revelation
Furthermore, if there are no differentiations within God, then there cannot be any differentiations within the mind of God. Consequently, without God being able to distinguish between His various thoughts and attributes, then, as in monistic pantheism, God would be utterly unknowable even to Himself.
And if God cannot know Himself, what hope do we have of knowing God? If God cannot distinguish His knowledge from any of His acts of power, it would be impossible for Him to reveal Himself to man. For instance, what does it mean to say that God is love if God’s love is identical to God’s omniscience? What would God’s omniscience mean if it was one and the same with God’s hatred? Terms describing God would cease to mean anything if they can mean everything. Thus, if God’s knowledge of Himself was restricted to a single attribute, then our knowledge of Him would be no knowledge at all. Without distinctions within God, says Calvin, “only the bare and empty name of God flits about in our brains, to the exclusion of the true God.”
Commenting on this, the Princeton theologian B. B. Warfield (1851-1921) remarked: “According to Calvin, then, it would seem, there can be no such thing as a monadistic God; the idea of multiformity enters into the very notion of God.” In this, Calvin understood that for God to reveal Himself to man, He must be tripersonal. Only a God whose diversity is equally ultimate with His simplicity is a God that can be known.
Jonathan Edwards also rooted divine revelation in the doctrine of the Trinity. According to Edwards, God is a communicative being. Expounding upon Edwards’ view, William Schweitzer writes: “In asserting that God is a communicative being, Edwards is referring to a logically and temporally prior theology whereby God is inherently communicative ad intra (i.e., internally) among the persons of the Godhead.” That is, although the economic Trinity communicates to man and angles ad extra (i.e., externally), God’s essential communicativeness is not dependent upon man or angels or anything else outside of Himself. This is because, ontologically speaking, the Father communicates to the Son, and the Son and the Father communicate to the Spirit. In this, communication is essential to the very nature of God.
Therefore, the economic Trinity is able to communicate ad extra (i.e., externally) to man, only because the ontological Trinity communicates ad intra (i.e.., internally) with Himself. The Father, Son, and Holy Spirit love, enjoy, and glorify each other by revealing themselves to one another, communicating to one another, and sharing themselves with one another. And it is only because they are inherently able to communicate and share themselves with each other like this that they are intrinsically able to communicate and share themselves with us, who are made in the image of God.
In other words, divine communication is possible because God is triune. As all three persons of the Godhead are involved in the process of communication: The Father reveals the Son (Matt. 16:17), the Son reveals the Father (John 14:6), and the Spirit reveals the Father and the Son (1 Cor. 1:30). Each person finds pleasure in revealing the glory of the other persons. Hence, we can know God because God is triune – something that could not be said about a monistic deity.
The Solution for Thoughts & Emotions
Also, a multi-personal God is required for a God who can differentiate between His different attributes, thoughts, emotions, and acts. Only a multi-personal God can have a will of decree and a will of command that allows Him to be both impassibly at peace in regard to the grand scheme of things and emotionally grieved in regard to particular sinful acts as they transpire in history. Like a 1,000 piece jigsaw puzzle that can either be fully constructed into a single picture or broken apart into its individual pieces, God is able to see all of history at one glance and also examine each singular event separately.
When He considers the complete historical picture, He is eternally happy. He is impassibly satisfied with the outworking of His will of decree because all things are working together for His glory as planned. And God is able to examine single pieces of the puzzle, independently from the whole, and be grieved accordingly. He can be angry with those who transgress His will of command because in those temporal moments He ceases to be glorified.
God’s essence does not change, but this does not mean that He does not have particular opinions/judgments about things that do change. The English puritan Stephen Charnock (1628-1680) understood that a display of changing emotions is not only consistent with the immutability of God but is required:
God is not changed, when of loving to any creatures he becomes angry with them, or of angry he becomes appeased…God always acts according to the immutable nature of his holiness, and can no more change in his affections to good and evil, than he can in his essence… Though the same angels were not always loved, yet the same reason that moved him to love them, moved him to hate them. It had argued a change in God if he had loved them always, in whatsoever posture they were towards him.
Consequently, God can be grieved after the fall of man and be appeased by the atoning work of Christ on the cross because He, who controls time, can differentiate between time related events.
The Solution for Relationships
The differentiation within the Trinity is also what allows God to be personal and relational in His nature. God did not have to take on relational properties when He created man; rather, He is eternally and inherently relational. Hence, without any change taking place in His nature, He is capable of personally interacting with those whom He created in His own likeness.
The Solution for a Separate Universe
The ontological differentiation between the Father, Son, and Spirit is as vital as God’s oneness. The ontological differentiation within God is vital in keeping the essence of God from becoming conflated with the universe. This is because the equal ultimacy of God not only allows for diversity-in-unity, but it also explains why an immutable God was able to create a distinct universe out of nothing (ex nihilo) at a particular point in time.
Aristotle believed that motion (e.g., the pure motion of the stars) was eternal, for every act of motion within the universe must be caused by a previous act of motion, which must be indefinite. Though motion is infinite, there must be a prime mover to prevent the logical inconsistency of an eternal regression. The solution, according to Aristotle, is that motion is the eternal effect of the eternal Unmoved Mover – making the unmovable God and the forever moving universe coeternal and coessential.
Aristotle was right – motionlessness and motion must both be eternal. There is no way around this. For instance, if motionlessness (i.e., an Unmoved Mover) was not eternal, then we would be left with an eternal regression of causes with no explanation of what or Who set off the first cause. On the other hand, if motion was not eternal, then motion would not be essential to God’s nature. And if motion was not essential to God’s nature, then God would depend upon something outside of Himself to move and act. And if God was immobile and unable to exert acts of volitional power, then He could not have created a temporal universe out of nothing. So, motionlessness and motion must both be eternal.
But how can both realities be eternal without God and creation being coeternal and coessential? How can an unmovable God create something temporal if creating the universe requires an act of movement within God? How can God be unmovable, yet capable of moving Himself to create? How do we have a God who is above time and space, but is not locked out of time and space? How do we have a God that is immutable to time-bound events, but is also able to carryout time-bound events, such as creating and governing the universe?
The only solution is found in the triune God of the Bible. God is immutable without being restricted to a static and motionless state. This is because God is one in His essence and three in His persons. He is unchanging in His essence (which safeguards us from open theism). However, in this immutable and eternal state of perfection, the Father, as a distinct person, is intrinsically and internally (ad intra) moved to love and glorify the Son, and likewise the Son and the Spirit are moved to love and glorify the Father. They each are incited to share, communicate, give, love, and glorify the other by the infinite worth that they consistently see in the other. They are in an eternal state of interacting and sharing their glory with each other. That is, within the Godhead there is an eternal state of movement (i.e., interaction) between the three persons without any change taking place in the unity of God’s immutable essence.
The word automobile originated from the compound of two French words auto, which means self, and mobile, which means movable. Thus, an automobile is something that moves itself. But truly this cannot be said of man-made vehicles that require a driver and fuel. Vehicles don’t move themselves. Strictly speaking, the word automobile applies only to God. Only the triune God is autonomously self-moving. Unlike Aristotle’s Unmoved Mover, the God of the Bible does not need the universe as a vehicle of movement. God is not dependent on anything outside of Himself. God is not cemented in an immovable state, for He can act, move, create, and do as He pleases.
To think, to love, to share, to communicate, and to act are all intrinsic abilities within a triune God. Because the triune God is not restricted from having acts of motion within Himself, creating and governing a universe that is separate and bound to time is not an impossibility. Creation does not have to be eternal. Although God is not bound by time and space, He is not locked out of time or space either. The God of the Bible is Lord of time and space as He is personally ever-present in all the particular affairs of this world.
In short, because the three persons of the Trinity interact internally (ad intra) with one another, the Godhead was able to create externally (ad extra) a temporal universe out of nothing at a particular moment in time.
The Solution for God and Time
This brings us to one of the most difficult questions of theology: What is God’s relationship to time? If time is the measurement of movement, then God’s relationship with time is unlike our relationship with time.
We are restricted by time because movement exists independent of our own existence. We can’t slow down the rotation of the earth or speed it up. Time ticks at the same rate regardless of how we feel about it. Moreover, movement changes us. We grow from young to old, with our bodies changing along the way. The older we become, the more we realize that our lives are slipping away from us. And there is nothing we can do about it. In short, we are bound to time because our existence is bound to causation or movement outside of our control.
God, on the other hand, is not moved or changed by any external causation or movement. This is because there is no causation or movement outside of God’s control. The causation within a solar system or the falling sand within a hourglass do not move (or even exist) independently from God’s will and power. Because God’s ontological existence stands independent of any external movement, His nature cannot be changed by movement or time. With this in mind, God’s nature is timelessly changeless.
The timeless and immutable nature of God, however, does not mean that God is restricted from moving Himself. Even though God cannot be moved or changed by external causes, He can internally move Himself in accordance with His immutable nature. This is because motion – all motion – occurs directly or indirectly by the power of God who does all things according to His predetermined counsel. As we have seen, God is capable of temporal acts of power (i.e., creating and governing the universe) because movement is inherent within His multi-personal existence.
So then, God’s relationship with time must be understood in light of His triune nature. While God is changeless in the singularity of His immutable nature, the interaction between the plurality of the divine persons is not static. In other words, God can be both timelessly changeless within His unified essence and capable of moving Himself due to the inherent interaction between the three divine persons.
Thus, time, as with movement, is neither something that exists independently of God nor is it something that restricts God. Rather, both time and movement are ultimately controlled by the interaction between the diversity of divine persons as they think and act in accordance with the oneness of their immutable nature.
The Solution for God’s Transcendence and Immanence
A monistic deity, on the other hand, would be completely locked out of time. An atemporal god, such a Allah, has its consequences. The consequence in this case would be that, since a monistic deity cannot display intentional and temporal acts of power, the universe would have to be eternal. That is, seeing that there is a universe, there could not have been a time when there was nothing but God if God was atemporal.
If God is bound by timelessness, where did the universe come from? The only possible answer that retains God as Creator is the notion that the universe has always existed as an eternal emanation flowing from the undifferentiated essence of this Unmoved Mover. As light flows from the sun, the universe has to be timelessly flowing out of God. Ultimately, without the Trinity, God and the universe would be one and the same, as light is made of the same stuff as the sun. Consequently, even though an atemporal god would be wholly other in His unknowable transcendence, He would be one with the universe in His ontological immanence. While this is a blatant contradiction, it is the result of a god who is barred from any temporal movement.
This obvious inconstancy, however, is safely resolved with the God of the Bible. With the Trinity there is a clear Creator/ creature distinction, since God created the universe out of nothing at a particular point in time. God alone existed before the foundation of the world. There was nothing else but God until God (at a particular point in time) freely and intentionally spoke the universe into existence out of nothing.
And because the universe and God do not consist of the same ontological substance, God remains transcendent. But He is also immanent because He is not barred from time as He personally interacts with those whom He has made after His own likeness. This unity and diversity between God and creation is possibly only because there is unity-in-diversity within the Godhead.
 By formal differentiation I mean something more than a conceptual distinction (distinctione rationis, a distinction in thinking) that exists only within our finite minds to help us make sense of an ineffable God that transcends human language.
 K. Scott Oliphint, “Simplicity, Trinity, and Incomprehensibility of God” in One God in Three Persons, Ed. Bruce Ware and John Starke (Wheaton, IL: Crossway, 2015), 230.
 The Eunomians (i.e., neo-Arians) denied the orthodox doctrine of the Trinity by applying Aristotelian logic to the doctrine of divine simplicity. In gist, they argued that if there are no distinctions within God, then only the Father exists a se (dependent on nothing outside of Himself). Ultimate oneness is reducible to the Father – He alone possesses the simple essence of Divinity. The essence of the Son is generated from the Father and the essence of the Spirit proceeds from the Father and Son as they are ontologically and eternally subordinate to the Father, who alone is Almighty God. See Thomas H. McCall “Trinity Doctrine, Plain and Simple” in Advancing Trinitarian Theology (Grand Rapids: Zondervan, 2014), 46.
 Scott Oliphint seeks to maintain balance when he reminds us: “An important aspect of this doctrine of God’s simplicity is that these distinctions in God are not thought to exist as real ‘things’ in God. That is, they should not be thought as things at all, so that the Godhead is a composition of ‘things upon thing’” (God with Us, 65).
 For an excellent article on the relationship between divine simplicity and the Trinity see Thomas H. McCall “Trinity Doctrine, Plain and Simple” in Advancing Trinitarian Theology (Grand Rapids: Zondervan, 2014).
 Cornelius Van Til, An Introduction to Systematic Theology, 2nd ed., William Edgar (Philipsburg, NJ: P&R, 2007), 273.
 B. A. Bosserman explained: “Unitarian theologies . . . succumb to a stultifying sort of mystery where god is identical with, or subject to, an ineffable void, that renders him incapable of speaking altogether, or of speaking with authority. For, nothing can be accurately predicated of a strictly unitary deity, since the multiplicity involved in predication is at odds with his nature. If such a being were to enjoy negative definition as he exists in contrast to the created sphere, it would only demonstrate his dependence on the temporal universe in order to enjoy the sort of differentiation, purpose, and relationship that he lacks in himself” (The Trinity and the Vindication of Christian Paradox, 101).
 B. B. Warfield, “Calvin’s Doctrine of the Trinity,” Works of Benjamin B. Warfield (Grand Rapids: Baker Books, 2003), 5.191.
 William M. Schweitzer, God is a Communicative Being: Divine Communicativeness and Harmony in the Theology of Jonathan Edwards (London: T&T Clark, 2012), 17.
 Stephen Charnock, The Existence and Attributes of God (reprint, Grand Rapids: Baker, 1996), 1:345.
 The proponents for open theism, such as Richard Rice, Clark Pinnock, and John Sanders, may say that God is unchanging in His essence, but they undermine their claim by making the diversity of the tripersonal relationship of the Godhead ultimate over the oneness of His unchanging essence. That is, the oneness of God’s essence ends up being at least partially absorbed into the diversity of God’s tripersonal interaction within creation. By elevating the diversity of God over the oneness of God, God’s sovereignty, omnipotence, and omniscience no longer remain immutable. God’s knowledge, emotions, and power become limited to the multiplicity of things taking place outside His being. Rather than being immutably closed, God is open to change. Rather than the Almighty controlling all things, He is more of a powerful demigod. He is able to properly adjust His plans as needed, but remains restricted to the diverse whims and decisions of man. His knowledge is dependent on creation.
The trinitarian God, however, is able to interact with creation in a personal and imminent way because He is inherently able to differentiate between things within Himself and things outside of Himself. Because diversity is essential to His nature, God is able to distinguish between His thoughts, emotions, acts, and time related events. Yet, He remains transcendent and separate from creation because His unity is also equally essential to His nature. Because He is able to differentiate between His will of decree and His will of command, He is able to providently and emotionally interact with creation in a personal way. But, He also knows and sees all things at once. And, ultimately, nothing can cause God to suffer because He knows and controls all things without there being any change within Himself.
In sum, without the diversity of the three persons, God’s simplicity would lead to pantheism. Conversely, without the oneness of God’s essence, the relational properties inherent within the Trinity would lead to open theism. Though from different directions, both pantheism and open theism make God dependent on creation. The equal ultimacy of the oneness and diversity of the Trinity is the only safeguard to keep us from falling on either side of the ditch.
 And according to Michael Reeves, love was “the motive behind creation” (Delighting in the Trinity, 47). For His own glory, God chose to share His love with His people. Or as Jonathan Edwards worded it: “God’s end in the creation of the world consists in these two things, viz. to communicate himself and to glorify himself. God created the world to communicate himself, not to receive anything” (Jonathan Edwards, Approaching the End of God’s Grand Design, 1743-1758, ed. Wilson H. Kimnach. vol. 25 of The Works of Jonathan Edwards. New Haven: Yale University Press, 2006., 116 ).