Lesson One
Lesson Two
Lesson Three
Lesson Four
Lesson Five
Lesson Six
2 Activities | 1 Assessment
Lesson Seven
2 Activities | 1 Assessment
Lesson Eight
The Church
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Lesson Nine
Humanity and Sin
2 Activities | 1 Assessment
Lesson Ten
The Work of Christ
2 Activities | 1 Assessment
Lesson Eleven
The Person of Christ
2 Activities | 1 Assessment
Lesson Twelve
The Holy Spirit
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Lesson Thirteen
2 Activities | 1 Assessment
Lesson Fourteen
Last Things
2 Activities | 1 Assessment
Lesson Fifteen
Theology Today
1 Activity | 1 Assessment
Course Wrap-Up
Course Completion
1 Activity | 1 Assessment


The Christian thinks and speaks of God in terms of Jesus Christ. She understands God to be God in this historical human being or, more exactly, to have His Deity in the self-defining decision and act of assuming flesh, of coming redemptively to humankind in the birth, life, death, and resurrection of Jesus of Nazareth. God is God-with-us, Immanuel. He is not God in aloof disinterest from creation or in pantheistic absorption into creation, but in His determinative self-election moment-by-moment to assume creation. He is Lord in being neither allergic to nor synthetically one with the creature, but in willfully existing in communion with us.

As we began to discuss last time, God is as He elects to be, not as we elect Him to be. He is not the output of human will, not a datum that we relate ourselves to as we choose, as if we naturally enjoyed the freedom to maintain an independence from God out of which we may or may not make ourselves dependent upon Him. Rather, that we exist at all is already declaration of the reality that God exists in willful self-determination to be Lord over chaos, darkness, and death, to be Creator, Reconciler, and Redeemer. In other words, we come to the doctrine of God through encounter with His revelation in Jesus Christ.

Our thought and speech are directed in Him to confession that God exists as Creator, the one who brings being out of nothing; that God exists as Reconciler, the one who sustains His creation and brings it into unity with Him; that God exists as Redeemer, the one who will restore creation and draw it into His eternal life.

The doctrine of the Trinity rises on the Christian horizon by virtue of the Word of God. This is true both logically and historically. Logically, recognizing the fact that God reveals Himself in Christ Jesus as God, which is to say, that He shows Himself to be God a second time, to exist in the freedom to be Lord in time as He has always been the Lord of time—this demands confession of both diversity and unity in God. It demands that we confess the differentiated distinctiveness of God in His life-acts alongside the sameness of God temporally and eternally. The factual reality of Christ Jesus as full God in full humanity teaches us that God is eternally Lord over humanity, that He is not subject to humanity or to any kind of anti-humanity but has always been humanity’s source and will always be humanity’s goal by now being humanity’s Savior. Who God was and who He will be are one with who He is in and as the Word.

Historically, the church did not clearly articulate and uniformly obligate a triune conception of God until the fourth century. The teaching came about in response to the contention that Christ Jesus was not fully equal and eternally one with God the Father. We will discuss this matter further when we come to the doctrine of the person of Christ in a few lectures. Suffice it to say that the doctrine of the Trinity emerged as the church was forced by internal conflict to decide what Scripture taught about Christ relative to the one and only God. We will briefly look to the Bible ourselves to rehearse what the church concluded.

As mentioned in our discussion of tradition in Lecture Four, the word Trinity nowhere appears in Scripture. It is a description of the total biblical picture of God, not a word given by God through the prophets and apostles. That fact does not so much grant us liberty to dispense with the term, as it obliges each new generation of theologians to return to the text in order to identify for themselves the vision of God that it expresses. It is best to understand the biblical picture of God as a development in human comprehension corresponding to God’s progressive revelation to successive generations. The development is from henotheism to monotheism to Trinitarianism.

Henotheism is the belief that there are multiple gods, but one deity is greater than the others. The term is composed of the Greek word hen, the neuter form of the number “one,” and theos, which as we have seen means “god.” One god is the supreme god, like Zeus among the mythological nature deities. Most scholars of the Old Testament agree that Abraham and the patriarchs were henotheists. We should not be offended by this observation. Abraham was called out of pagan, idolatrous Sumeria, a polytheistic world of territorial gods demanding various forms of religious sacrifice and supplication. Why should we expect that upon his encounter with the one true God, Abraham immediately gave up the entire framework of his former worldview? Why should we not allow God to work within what Abraham comprehended even as he intended to correct Abraham’s understanding? Is that not how He always has worked? Have we not learned that God placed Himself in the womb of a sinful, peasant virgin, but as her Lord, the condition of her correction, healing, and exaltation along with the correction, healing, and exaltation of all humanity?

We can see the apparent henotheism of the patriarchs in accounts like that of Jacob’s dream in Genesis 28:10-22. The Hebrew in these verses switches between two important words: “Elohim,” plural of “el,” which means “gods” but is also indicative of a singular deity depending upon context, and “YHWH,” the untranslatable name of God eventually given to Moses in Exodus 3. YHWH is from the verb “to be” and thus means “He is” or “I am” depending upon its given form. It appears in most English Bibles as the word “LORD” in capital letters. So God identifies Himself to Jacob in verse 13 as this God, YHWH or the LORD. “I am the LORD [YHWH],” He says, “the God [Elohim] of your father Abraham and the God [Elohim] of Isaac.”

Impressed by his encounter with the Lord, Jacob makes a vow in verse 21. If God stays with him, provides for his needs, and gives him success on his journey to find a wife in the foreign territory of his ancestors, then “the LORD [YHWH] will be my God,” he says. Jacob apparently believes that there are other gods or versions of el besides YHWH that could be his God, but YHWH can prove His greatness over these other options by caring for him on this treacherous undertaking, in which case He would be worthy of Jacob’s worship and devotion as He was worthy of Isaac’s and Abraham’s.

Scholars disagree about how long it takes for the henotheism of the ancient Hebrews to give way to full-blown “monotheism,” the belief that there is only one God and that all other claims to deity are false. Some see it in nascent form during the time of Moses, exhibited in verses like Deuteronomy 4:28 where the deities of foreign nations are described as “manmade gods of wood and stone, which cannot see or hear or eat or smell.” Monotheism certainly is present in the Old Testament by the time of the major prophet Isaiah. In Isaiah 45:5, the Lord rebukes the idea of other deities, saying, “I am the LORD, and there is no other; apart from me there is no God.” He says the same thing in verses 18, 21, 22, and 24, and variously restates the truth throughout chapters 46–55.

An important feature of the Old Testament witness to the one God is the way that it employs the three modalities of word, wisdom, and Spirit. God creates through His word by the power of His Spirit, or something along those lines, in Genesis 1. The word of God nourishes (Deut. 8:3), and brings forth life like rain from heaven (Isa. 55:11). Job teaches that wisdom cannot be found, bought, or quantified, for it is the exclusive provenance of God (Job 28:12ff). Jeremiah says that God founded the world by His wisdom (Jer. 10:12). Job contends that “the Spirit of God” made him (Job 33:4). The psalmist pleads for God not to take His Spirit from him (Ps. 51:11). And Joel prophecies about new creation in the Spirit poured out on all flesh (Joel 2:28ff).

This Old Testament testimony is unclear, it would seem deliberately so, about whether God’s word, wisdom, and Spirit are manifestations of God, or attributes of God, or both. We cannot say that the Old Testament authors were consciously Trinitarian in their understanding of God or anything like that.

But collectively their witness does provide a pregnant backdrop for the Trinitarianism of the New Testament authors.

We have already encountered the way that John considers God’s Word to be both a second alongside God and one with God. John further teaches that Jesus understood Himself as distinct from the Father, able only to do the Father’s will, for instance (John 5:30), and yet fully revealing of the Father (John 14:9). Indeed, John records Jesus employing the Greek, “ego eimi,” equivalent of the Hebrew YHWH, of Himself. Jesus refers to Himself as the great “I am,” literally dozens of times in John (see for starters 4:26; 6:20, 35, 41, 48, 51; 8:12, 23 [twice], 24, 28, 58; 10: 7, 9, 11, 14; 11:25; 13:19; 14:6; 15:1, 5; 18:5, 6, 8).

The early church also used language of Christ that was appropriate only to use of God. The New Testament scholar Larry Hurtado has pointed out that the earliest Christian confession was that “Jesus is Lord.” Paul certainly spoke of Jesus this way (e.g., 1 Cor. 12:3; Phil. 2:11). In his letter to the Philippians, Paul teaches that Jesus possessed a kind of natural equality with God, but that He submitted Himself to the form of a servant, taking up human flesh (Phil. 2:6-11). Similarly, in Colossians 2:9, Paul indicates that the fullness of God lives in Jesus in bodily form. And the author of Hebrews connects Jesus to the prophetic Psalm 8, saying that He is both crowned with glory as Lord over all and “a little lower than the angels” (Heb. 2:5-8).

Because of the scriptural witness to Christ’s oneness with and distinction from God, the earliest church formulated proto-trinitarian tidings. “May the grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit be with you all” (2 Cor. 13:14). It also commanded baptism in an incipient Trinitarian formula. “Therefore go and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit” (Matt. 28:19).

In sum, the church identified in Scripture the reality of the one and only God, the great “I am,” who unites Himself in covenant with Abraham and his offspring, fulfills His responsibility and position in that covenant in the Messiah, Jesus, making a new covenant with humankind that He will bring to consummation in His Spirit. It identified the one God in three modes or ways of being: the Creator and covenant maker, the Reconciler and covenant fulfiller, and the Redeemer and covenant achiever.

The church did not find three gods in the Bible, but one. Again, Christ Jesus is identified with YHWH; He is not presented as another god in addition to YHWH. And it did not find one God playacting in three subsequent roles, but three manners of distinctive subsistence in the one God. Jesus defers to the Father, prays to the Father, and stands in relationship to the Father; He does not substitute for or replace the Father. It therefore articulated a triune or “three-in-one” teaching concerning the biblical God.

Trinity describes the reality that God is one being eternally existing in three persons. This is the traditional language: “being” and “persons.” Even though we stand at some distance from the philosophical milieu in which they were forged, it is best to learn these terms as a baseline. They are quite precise, intended to prevent misconceptions.

“Being” refers to God’s eternal essence or nature. In His substance, His God-ness, that which makes deity of “deity,” God is one. He is not partitioned or a composite of elements. God is not made of three ingredients—one measure of Creator, one of Reconciler, and one of Redeemer—which, when mixed together, form God. No, He is “maximally” one or “simply” one, as the medieval theologians used to say. He is singularity in the utmost.

If He was only God in composition, fully divine when all the parts were present, then each part would not be divine in itself. The Creator would not be God, but only potentially God, only a lock in need of a key or a key in need of a lock and never full, functioning deity in Himself.

To express the maximal oneness of God, medieval theology formulated a rule, which will sound abstract and overly philosophical at first, but continues to have a good deal of value for us. “Every operation of the Deity outside Himself is one,” they said. Whenever and however He acts, wherever and however He exists in His covenant history, God is one. In His acting as Creator, for example, God is also Reconciler and Redeemer. The Reconciler and Redeemer do not wait for the Creator to finish so that they can get on with their work, but are fully active, fully participative in the work of creation. Similarly, the Creator and Reconciler are not waiting in heaven for the Redeemer to bring creation under the final lordship of God, but are fully active, fully participative in the work of redemption.

The church introduced the term perichoresis to further express the mutuality inherent in God. Pictorially, this refers to a kind of divine dance in the round. It means more exactly that each of the divine persons indwells the other two. The Reconciler and Redeemer dwell in the Creator; the Creator and Redeemer dwell in the Reconciler; the Creator and Reconciler dwell in the Redeemer. We glimpse this reality in passages like John 10:30, where Jesus says, “I and the Father are one,” and John 20:22, where Jesus breathes the Holy Spirit on His disciples. “Persons,” therefore, are not to be thought of as parts of God, as I sometimes hear them called. Neither are they “members” of an exclusive club.

Rather, “person” refers to the individuated form of substance. It is from the Latin persona, which connotes “personality,” although we cannot be minimalists in understanding that word. Person does not mean mere behavioral tendencies, as we usually think of it. In its formal, dogmatic usage, “person” means something like the holistic entirety of qualities that define and differentiate one from the whole.

Thus, for instance, the Reconciler is not a mere behavioral pattern in God, as if God simply tends to care for His creature but might do otherwise. Rather, the Reconciler just is the individuated form of God’s essence as Savior. He is the entirety of those qualities that define and differentiate God before us as creation’s sustenance, its means of rescue from darkness and nonbeing.

In this regard, the persons stand in an eternal relation to each other. The Reconciler simply is the holistic complement to the Creator and Redeemer. The same is true of the Creator relative to the Reconciler and Redeemer and the Redeemer relative to Creator and Reconciler. To be precise, the Reconciler simply is the repetition of the Creator in differentiated form, that is, He is the reiteration of the Creator’s life as the cause of existence in the form of creation’s sustenance and union with God. So also with the Redeemer: He is the repetition of the Creator and Reconciler in distinct form, that is, He is the reiteration of the Creator’s and Reconciler’s work in the form of making creation subject to the lordship of God in Christ Jesus.

Here again, medieval theology gave a rule to guide our thinking and speaking of the divine persons. “The only basis for distinction in God is the relations,” they said. They meant that, strictly speaking, the persons simply are the relations by which the one God exists in self-differentiation. Diversity in God consists only of the reciprocal definition among His life-acts. Once more, the persons are subsistent differentiations in the life-giving being of God.

If we were to transition our thought to the inner life of God, we would say that the Father strictly is paternity, or the condition of being parent. The Son strictly is filiation, or the condition of being child of the Father. And the Spirit strictly is spiration, or the condition of being breathed by the Father and Son. Eternally, God stands relative to Himself in these modes of being.

Whew! There’s a lot to this doctrine of the Trinity, isn’t there? In fact, we’ve only covered some of the basics! We have not considered the relationship between God in eternity and God in time and the rule that the immanent Trinity is the economic Trinity but perhaps not vice versa.

We’ve not addressed the disagreements between Eastern and Western Christianity on threeness and oneness, on the nature of “hypostases,” or the “filioque controversy” over whether the Spirit proceeds from the Father only or also from the Son. These are interesting matters of study, but better reserved for a more advanced course. Just covering what we have, you might already be wondering about the relevance of all these precise words, rules, and formulas.

There are three reasons why the doctrine of the Trinity merits such detailed study. First, we want to do everything possible to communicate the biblical picture of God accurately and faithfully. The disciple of the Word is concerned to have her knowledge of God given and shaped by the Word, as we have discussed. She seeks to grow in the Word, not merely to give tacit approval to it. She endeavors to respond to the Word in the fullest range of comprehension possible.

Thus she tries to avoid lazy missteps when it comes to Scripture’s revelation of God. The church has fenced off two principal directions in its confession of the triune Lord. The consummate Trinitarian heresies are tritheism on the one side and modalism on the other.

Tritheism loses the oneness of God in its affirmation of His threeness. Scripture does not present three gods, but one. We are not dealing with three beings, but one being in three Persons. Modalism loses the threeness of God in its affirmation of His oneness. Scripture presents three eternal Persons in one being, not one Person wearing different costumes. The Son and Spirit exist eternally with the Father and are fully equal to Him.

They do not come into being at some point, nor are they mere extensions of the Father, but fully and totally the one God in themselves, as is the Father. Avoiding these heresies, we again are confronted with the dialectical nature of Christian theology. Our task is to confess both God’s oneness and threeness, not compromising a single degree on either side. We neither contend that God is really three and His oneness is a façade, nor that He is really one and His threeness is a façade. God is one being in three eternal persons.

Secondly, our understanding of God’s life surely must inform the way that we construe and conduct our own lives. Surely it matters to us that God exists in eternal mutuality, for instance, and that He wills not to be God in another way. It means something that there is no strife or rivalry in God, but perichoretic unity and complementary deference to the other. Surely this vision of our Lord casts a corresponding vision for us. We will explore this more fully in our next lecture.

Thirdly, the triune God is the Lord of covenant history. We do not arrive at the doctrine of the Trinity by speculation in a vacuum, but by concrete encounter with the God who has His being as Creator, Reconciler, and Redeemer. Our account of God does not waft in on the wind of reason, or bubble up from the recesses of introspection, or drop in from heaven in an epiphany, but derives from the Word Jesus Christ who is with God and is God. We know God in the event that He confronts us in Christ, in the happening of His self-determinative life-act. We know Him in the ongoing execution of His eternal decision to be this God, of His self-election to be Immanuel. And as we now must discuss, we know ourselves in the same event.

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Lesson Materials

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