The Doctrine of the Trinity at Nicaea and Chalcedon

An in-depth look on how the early church took both the Bible and rationality seriously and used the Bible as the authority and source of doctrine in working out the details of the doctrines of the Trinity. 


The formulation of the doctrine of the Trinity is a history of the refinement of terms and philosophical categories. Proper terminology was a primary issue of the ecumenical councils of the fourth and fifth centuries, and so was precision of thought and the philosophical categories used to characterize the Trinitarian and Christological doctrines. The Council of Nicaea resolved the question of Jesus’ deity, but led to further dissent about Jesus’ human and divine natures. These issues culminated in the expression of the doctrine at Chalcedon.

The impressive thought and debate that went into the Councils of Nicaea and Chalcedon produced biblically sound, but also intellectually virtuous doctrines. F.F. Bruce expresses the importance of accurate language in the creeds: "Inasmuch as the deity of Christ and the doctrine of the Trinity are embedded in the New Testament, although not explicitly formulated there, we must make the effort of wrestling with difficult terminology if we are not to fall an easy prey to misunderstanding or to actual heresy." Doctrinal development requires rigorous intellectual skills and sound philosophic categories to accurately apply God’s revelation. Thomas Torrance underscores the importance of applying good reasoning to theology so that the rationality of God can “throw its masterful light upon the whole area of human experience and knowledge.” The struggle for clarity of terms and thought in the expression of the orthodox doctrine of the Trinity and Christology helped build a solid doctrinal foundation that is also marked by its philosophic soundness. The development of rational doctrines is an example of creative interchange between theology and philosophy where both disciplines contribute equally.

The Historical Foundation of the Doctrine of the Trinity

The doctrine of the Trinity developed from implicit to explicit form in the early centuries of the church and was not invented at Nicaea. The early church believed the doctrine in its general form based on the revelation of Scripture. The foundation of the early doctrine of the Trinity was the baptismal formula and the doxologies in the Epistles along with the Logos-doctrine of John. The earliest confessions professed Jesus to be God. Peter exclaimed, "You are the Christ, the Son of the living God" (Matthew 16:16), and the eunuch whom Phillip baptized confessed his belief,: "I believe that Jesus Christ is the Son of God" (Acts 8:37). Admission to the church was connected with belief in the doctrine of the Trinity as evidenced by the early baptismal formula that was used in accordance with the command of Jesus in Matthew 28:19. The doctrine of the Trinity was essential from the beginning of the Christian Church.

The earliest of the formal creeds, The Apostle’s Creed, have the Trinitarian elements that would be developed later. However, there was no need for a technical definition of the Trinity during the first two-and-a-half centuries until heresies arose challenging Jesus' divinity. Shedd says that belief in the Trinity “started not so much with three Persons as the deity of the Son. It is indisputable that they [the early church] worshipped Jesus. They emphasized the deity of Jesus as much or more than the Father in the early church. The incarnation is the great dogmatic idea of the first Christian centuries and shapes the whole thinking and experience of the church." The person of Christ was the catalyst for the Trinitarian debate. Consequently, the person of Christ would follow quickly after the Trinity as needing more precise expression, which the early church was fully equipped to do with their theological and philosophical skills.

The Apostles' Creed was used by the early church from the second century and was probably condensed from the Apostles' writings. The creed is very clear and concise concerning the essential doctrines of Christianity. It teaches the existence of God as Father, Son, and Holy Spirit. The biblical language of the Apostles' Creed was sufficient for the time; there was no need for exact and rigorous Trinitarian distinctions until heresies arose.

The Apostolic Fathers freely applied the term “God” to Jesus in the strict sense of divine substance. They admitted to only one divine substance and confined worship to the one true God, yet worshipped the Son. They attributed the properties of the divine essence to the Son.

Origen’s Contribution

Improper exegesis was responsible for the heresies that arose after the early period of the Church. Monarchianism, the denial of the plurality of persons of the Trinity, cited only those texts that teach the unity of God and neglected the others that imply His real and not modal trinality. Arius followed the other extreme with the same type of one-sided exegesis and asserted the distinct personality of the Son at the expense of His unity of essence with the Father. It was necessary for the Nicene Council to employ an all-encompassing exegesis of the biblical data and assert consubstantiality and hypostatical distinction. This required not only sound exegesis, but accurate translation into terms and categories that expressed the data in the Bible. It required sophisticated linguistic and philosophical acumen.

Origen's work marked a significant milestone in the doctrinal expression of the Trinity. Origen (c. 185-c. 254) taught at the Catechetical School at Alexandria, which reached its zenith under his tutelage. He emphasized the hypostatical distinctions between the persons of the Trinity; however, he laid the groundwork for the radical errors that required a whole century of discussion to work out. Arius cited Origen as his authority to support his view that the Son is finite and created. Athanasius also claimed Origen taught the same doctrine as he.

Despite this confusion, Origen gave the church the best way to harmonize the biblical terminology of the Father and the Son. Origen provided the key that the Son is homoousios to the Father, of one substance or essence with the Father. But Origen was speculative in his theology and carried his interpretations beyond the literal content of Scripture to allegorical extremes. In 553 Origen was declared a heretic.

Origen’s influence on the future debate, however, is indisputable. He captured the idea of Sonship by making a sharp distinction between three hypostases, a term not previously employed. He maintained three divine hypostases or personal substances. These categories provided the framework for the subsequent refinement at Nicaea.

The Arian Controversy

The Council of Nicaea was motivated by the Trinitarian debates propelled by the views of Arius (256-336). The purpose of the council was to clarity the orthodox doctrine of the Trinity. Arius' desire was to make the relation of the Father to the Son comprehensible. Arians equated the limits of their understanding with the limits of reality. What they could not conceive could not be. But the Arians also neglected the distinction between the rationality of an idea and the ability to fully comprehend it. Christian theology is utterly rational, despite the inability to fully comprehend all of the implications of a biblical doctrine.

Arius believed that the Father and Son were of similar substances, but Jesus did not share in the same divine substance of the Father. Jesus was not fully divine in the same way as the Father. Arius denied both the personality and deity of the Spirit. He considered it to be God's force, not personal and not God, but the power by which God worked in creation. His views were condemned by the Synod of Alexandria in 321, but the spread of Arianism made it clear that the Apostles' Creed was no longer sufficient to protect orthodoxy. The Arian controversy motivated the church to define the standard of the doctrine more explicitly.

Athanasius was Arius' principle foe at Nicaea. Louis Berkhof points out the significance of Athanasius’ defense: "He felt that to regard Christ as a creature was to deny that faith in Him brings man into saving union with God." Athanasius was primarily responsible for bringing about the condemnation of Arianism at the Council of Nicaea by mounting the defense of orthodoxy. Athanasius argued mainly from Scripture, but also employed sophisticated philosophical arguments. He is regarded as the greatest theologian of his time.

Church representatives from all over the known world were invited to attend the first ecumenical council. They met at Nicaea in Bithynia from early May to late June, 325 A.D. ; 318 bishops were in attendance, 1/6 of the whole body of bishops. There were three basic parties represented at Nicaea, each with a particular theological concern in defining the doctrine of the Trinity. The first group was made up of true Arians, who were vastly outnumbered. A second group was the Nicenes, represented by their leader Athanasius. A third group, led by Eusebius of Caesarea, was named the "homoiousions" (defined below) for their favor of the term. Athanasius persuaded many of the middle-of-the-road homoiousions to take the homoousion position, so the second group gained a majority giving them a decisive advantage at the outset.

The Nicene Solution

The purpose of the Nicene Council was to faithfully express the teaching of Scripture and clarify the doctrine of the Trinity as completely as possible. They took pains to demonstrate that their views were Biblical and apostolic in origin. The Council formulated a creed that would serve as an authoritative guide in reading and interpreting Scripture. Their view of faith included rational activity; it involved "acts of recognition, apprehension and conception, of a very basic intuitive kind, in the responsible assent of the mind to truth inherent in God's self-revelation to mankind." For this reason, it was essential to the Council that they represent the Biblical witness in an intellectually respectful way, so the tools of reason and philosophy were employed to work out the doctrine of the Trinity in a rigorous and accurate manner.

The controversy between the parties at Nicaea raged over the proper term to express the kind of substance that the Trinity shares. The debate focused on the terms homoiousios and homoousios. Though the words look very similar, they were a world apart in what they conveyed about the nature of Jesus. The difference was whether the Son is of the same or a similar substance with the Father. Athanasius and his party favored the term homoousios, "of the same essence," to describe the relation of the Son to the Father. This term identified the Son sharing the same essence with the Father as uncreated and necessary in His existence. This is the term that Origen had used a century earlier to explain this relation. The Arians preferred the term homoiousios , "like the Father" or "of a like essence with the Father." The presence or absence of one letter made all the difference to say whether the Son was similar or identical to the divine essence.

Christology was central to the debate. The chief concern of Athanasius’ group was the relationship of Jesus' deity to the doctrine of salvation. The Nicene Fathers considered the work of salvation the type of work only God could do. Only God could save because God is the offended party. The grace of Jesus Christ is the very grace of God Himself. As Athanasius said, "No creature can be saved by a creature." How could it be the grace of God to pour out His wrath on an innocent third party? Jesus is a mediator in the full sense of revealing God himself because He is God.

As a direct response to Arianism on this point, the Council added the phrase "the Son is begotten from the Father, God of God, Light of Light, very God of very God, begotten not made." This last statement was added to define the idea that the generation of the Son was an internal, necessary, and eternal act of God. The phrase precluded the possibility of misinterpreting it for creation of a temporal and finite substance or the generation of a secondary substance of a hybrid kind. Shedd points out the significance of this addition, "This phrase contained the metaphysical kernel of the dogma, and was the crucial test of Trinitarian orthodoxy and heterodoxy." The words they chose expressed precise philosophical categories of existence that were essential to the doctrine so that there could be no misunderstanding of the orthodox view.

Little discussion took place at the Council of Nicaea regarding the Holy Spirit. First, there was not as much agreement on the relation of the Spirit in the Trinity as there was regarding the Son. Secondly, Athanasius and others who held to an orthodox view understood that once it is established that Jesus is of the same essence as the Father, it naturally follows from the biblical data that the Spirit is as well. Once they demonstrated the Biblical and philosophical possibility of two persons of the divine substance, it was a small step to demonstrate the third person. The Arians could no longer hide in ambiguous language with the application of the term homoousios.

The vast majority of the participants signed the creed, but instead of settling the controversy, the Council of Nicaea initiated a half century of theological turmoil that was marked by political interference and changing fortunes for Athanasius and Arianism. The tide of the controversy rose and fell with the theological sympathies of the emperors. One hundred fifty bishops met in 381 at Constantinople and declared the faith of the Nicene Creed in its original form as the sole legal religion in the empire and condemned all forms of Arianism.

The Chalcedon Conclusion

The Council of Nicaea defined the Biblical doctrine for the Trinity by focusing on the identity of Jesus, but it was not within the scope of the council to define Jesus’ humanity and the relation of the two natures to each other. The Trinitarian doctrine had significant implications for Christology that was addressed at Chalcedon in 451 A.D. The council wrestled with how one person, Jesus, could have two natures. If Jesus is the same homoousios with the Father and is God, this must be reconciled with Jesus’ clear humanity as evidenced in the Gospels.

Chalecedon was directed at the Nestorian and Eutychean heresies, which concurred with the Nicene Creed but worked out Jesus’ deity in false relation to His humanity. Nestorianism’s error was the failure to unite the two natures in one person. Each nature represented separate persons somehow possessed by the man Jesus. The other heresy, Eutycheanism, drew the opposite conclusion. In this case, the human nature was subsumed by the divine nature making a hybrid and unique kind of nature. The solution at Chalcedon was to strike a Scriptural balance.

The solution sought at Chalcedon affirmed the unity of Jesus’ person and the duality of His natures, and His identity with the divine substance. Four factors need to be balanced for an accurate understanding of Jesus: deity, humanity, the unity of one person, and the distinction of the two natures. This has been called “the Chalcedonian box” that defines the boundaries of orthodoxy and within which the answer must be found. The Chalcedonian creed falls short of plumbing the depths of the full implications of this doctrine (no doctrine can), but it lays out the essential elements of Christology and defines the boundaries of error. Shedd underscored the importance of Chalcedon, “It substantially completes the orthodox Christology of the ancient Church.”

The Philosophical Categories

The ecumenical councils used Scripture as their authority, but sought to work out the details in an intellectually rigorous way. The early theologians were also philosophers, and brought
these categories of thought to bear on the debates. After all, if God is a rational being, His revelation must make logical sense, though this is different than being fully comprehensible to finite minds. If doctrines really “were inconsistent, then it could not express the central truth of the Christian religion and necessarily at least some of the claims made in stating the doctrines would be false.” So theology and philosophy must interact to express the most accurate and logical doctrines possible. The orthodox doctrines were worked out using philosophic categories of person, substance, and nature.

A person is a category of immaterial conscious substance. There seem to be three types of persons that we know of: God, angels, and humans. Persons are essentially souls. There are some capacities that are common to all persons: cognition, rationality, affect, volition, desire, perception, and morality are examples. The possession of these capacities qualifies a being for personhood. Jesus is a person in virtue of being God, therefore He is of the same type of conscious being as humans. It would not be appropriate or possible for Jesus to become a non-person, for instance an animal or a non-conscious thing, to initiate salvation.

Substances, or substantia, possess properties that make a thing what it is. The substance remains identical to itself through time and change. A substance is a natural kind that is marked off by “a set of its ultimate capacities that are possessed by it solely in virtue of the substance belonging to its natural kind.” Membership in the natural kind is constant through a person’s existence, it tells us what a thing is, and membership in the kind is the ground of identity through change. A substance cannot lose its essential properties and continue to exist. This is necessarily true if Jesus is to remain identical to the second person of the Trinity through the incarnation. The Council of Nicaea affirmed that Jesus was of one substance with the Father and the Spirit; He shares in the divine essence and continued to through the incarnation.

A nature is a set of essential properties that further mark off what sort of thing an individual substance is. The distinction between kinds of personal substances is the unique natures they possess. Orthodoxy holds that all of God’s properties are essential, but angels and humans have essential properties in virtue of their natures and accidental properties in virtue of their individual existence. Among God’s necessary properties are perfection, omniscience, omnipotence, and omnipresence. Jesus could not lose these and continue to be homoousios to the Father, so somehow these divine properties coexisted with the human nature in the Jesus.

To understand how the second person of the Trinity could take on humanity, we must understand the difference between essential and accidental properties. To determine what are the essential properties of human nature, we must take into consideration the distinction between what is universal to all humans versus what is essential to all humans. Thomas Morris points out that it is universal that all human persons live on the surface of the earth, but that does not mean that it is essential that they do. Humans could live in a space lab for their entire bodily duration and still be human. It is also the case that all humans sin, but that is a universal property not an essential one since it is possible for humans to live without sin. Morris points out a further distinction that follows from this, “In order to be fully human, it is not necessary to be merely human. An individual is merely human just in case it has all the properties requisite for being fully human…and also some limitation properties as well.” This distinction will be helpful in solving issues of apparent incompatibilities between divine and human natures. Jesus is fully human, all that humanity was meant to be; the rest of the members of the human race are merely human, limited by the influence of sin.

The best test for determining what is essential to human nature is conceivability: Is it possible for human beings to exist without a particular property? When this test is administered to many properties that appear to be essential to humanity, it becomes clearer that many are actually accidental. Certainly it is conceivable that humans could exist without sin; in fact, this is the witness of Scripture in the Garden of Eden. So it would be fully consistent for Jesus to take on humanity that is somewhat different from the universal experience of the human race. Jesus would only have to take on the properties essential to humanity.

With this framework set, we can propose an analysis of what a human being is. A human is a personal substance that possesses the set of essential properties of human nature, and is embodied in its usual state of existence, but not always so. Jesus was fully human by this analysis. He retained the divine substance necessarily, and added human nature, remaining one person.

Unique, Yet Rational

God is a personal substance, but instead of the usual one-to-one correspondence of persons and substance that we are familiar with, God is three persons in one substance. The divine nature, shared by all three persons of the Trinity, is able to be instantiated only once. God is a union of three persons. The witness of the Bible is that God is one (Deut. 4:35). It also seems necessarily true that there can only be one being with the divine essence if God’s maximal attributes are understood in a comparative sense. Part of the logic behind the Nicene Creed is that it was necessary for Jesus to be God. If Jesus made claims to divinity and was a separate person from the Father, the divine substance must admit of multiple persons. It was also understood that only God could affect salvation for humanity. A mere human could not accomplish the task.

Though unique, there appears to be no incoherence to the concept of three persons in one substance. Each personal substance of the Trinity has the essential properties of divine nature.
Each person of the Trinity is a center of consciousness with His own personal capacities. Jesus is a preexistent divine personal substance with two natures - a divine nature that added a human nature to His substance. Again, though it is a unique case for a person to have two natures, it seems possible for two personal natures to be coexemplified as long as their essential properties are not mutually exclusive. Because the second person of the Trinity had the same personal substance as the incarnated Jesus, they are identical persons. Though this person added a new nature, His essential properties did not change. Because natures are essential properties that cannot be lost without going out of existence, Jesus continues to have two natures. The incarnation could not be a temporary event, which is what orthodox doctrine holds.


The early church took both the Bible and rationality seriously. The Bible was the authority and source of doctrine. But the early church was not fideistic; they brought rigorous theological and intellectual efforts to bear in working out the details of the doctrines of the Trinity and the implications this had for Christology. This approach was essential to define orthodoxy and
defend the church against heresy. The Bible witnesses to the concept of the Trinity and a person with two natures and the doctrines bear up under philosophic scrutiny. The ancient creeds of Christendom and the articulation of two of the most fundamental Christian doctrines are found to be rational and commendable.

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Melinda Penner