The outline is by no means exhaustive but rather was meant to serve as a guide on several issues we thought were important to discuss. I appreciate any comments or feedback on the content.
I. Quick Facts
a. The word “Trinity” refers to “Tri-unity” (three in one).
b. The term comes from the Latin trinitas.
c. The doctrine of the Trinity is a central doctrine of the Christian faith.
i. “‘Central doctrines’ of the Christian faith are those doctrines that make the Christian faith Christian and not something else.”
ii. No other religion holds to this teaching.
d. The first recorded use of the term “Trinity” is by Theophilus of Antioch (116-181) in the second century.
II. What Are They Saying About the Trinity?
a. Jehovah’s Witnesses
i. “To worship God on his terms means to reject the Trinity doctrine. It contradicts what the prophets, Jesus, the apostles, and the early Christians believed and taught. It contradicts what God says about himself in his own inspired Word.”
ii. “Never was there a more deceptive doctrine advanced than that of the Trinity. It could have originated only in one mind…the mind of Satan the Devil.”
i. “Unbelievers are those that say: ‘God is one of three.’ There is but one God. If they do not desist from so saying, those of them that disbelieve shall be sternly punished.”
ii. “They do blaspheme who say God is one of three…for there is no God except one God.”
c. Thomas Jefferson
i. “When we shall have done away with the incomprehensible jargon of the Trinitarian arithmetic, that three are one, and one is three;…and got [sic] back to the pure and simple doctrines [Jesus] inculcated, we shall then be truly and worthily his disciples.”
III. The doctrine of the Trinity
a. A Basic Definition: “Within the one Being that is God, there exists eternally three coequal and coeternal persons, namely, the Father, the Son, and the Holy Spirit.”
b. The doctrine of the Trinity is a logical deduction based on three lines of evidence presented in the Bible:
i. There is one God (Deut. 6:4; 1 Tim. 2:5; James 2:19).
ii. The Father is God, the Son is God, the Holy Spirit is God (John 8:58; Acts 5:3-4; 1 Cor. 1:3; Eph. 4:30; Col. 2:9; 2 Peter 1:17).
iii. The Father, Son, and Holy Spirit are distinct Persons (Matt. 3:15-17; Matt. 28:19; John 16:13-15; 2 Cor. 13:14).
c. God is Triune: “He exists eternally and simultaneously as three distinct and distinguishable persons (though not separate): Father, Son, and Holy Spirit.
i. All three persons in the Godhead, or Divine Being, share equally and completely the one divine nature, and are therefore the same God—coequal in attributes, nature and glory.
ii. God has revealed himself as one in essence or substance (being), but three in subsistence (personhood).
iii. In terms of what God is (essence), God is one; in terms of who God is (subsistence), God is three.”
d. “We worship one God in the Trinity, and the Trinity in unity; we distinguish among the persons, but we do not divide the substance…The entire three persons are coeternal and coequal with one another, so that…we worship complete unity in Trinity and Trinity in unity” (The Athanasian Creed).
e. “Trinity can thus be defined as three persons in one divine essence or as one divine essence subsisting in three modes, the unity of essence being guaranteed by the consubstantiality and coinherence of the persons, the distinction of persons being manifest in their relations.”
IV. Reason and Logic
a. “Human reason cannot reveal anything, but it can defend what has been revealed.”
i. In other words, human reason is not limitless.
1. We would never reason our way to the Trinity (though some Christians in church history believed we could, e.g., Anselm).
2. We know God is Triune because He has revealed His nature to us through special revelation, i.e., the Bible.
ii. However, once the doctrine of the Trinity has been revealed it can be defended using reason.
1. This is because it is not logically contradictory.
2. The Trinity is not irrational but suprarational.
b. The law of non-contradiction
i. “A and non-A cannot both be true at the same time and in the same sense.”
ii. Examples of contradictions
1. God is one God and three Gods
2. God is one Person and three Persons
iii. In order for something to qualify as a contradiction it must violate the law of non-contradiction
c. Is the Trinity a logical contradiction?
i. The doctrine of the Trinity says there are three persons in one divine essence.
1. This is not contradictory because it distinguishes between the concepts of person and essence.
2. “…while God is one and many at the same time, he is not one and many in the same sense. He is one in the sense of his essence but many in the sense of his persons.”
ii. The “Is” of predication vs. the “Is” of identity.
1. It is correct to say “Jesus is God” but not “God is Jesus.” Why?
a. Because to say “Jesus is God” is to predicate to Jesus the divine nature which two other Persons posses: the Father and Holy Spirit.
b. But to say “God is Jesus” in terms of identity is incorrect because Jesus does not exhaust what it means to speak of God.
2. Therefore, logically speaking, we can affirm:
a. “The Father is God,” “The Son is God,” and “The Holy Spirit is God” using the “is” of predication.
b. “The Father is not the Son,” “The Son is not the Spirit,” and “The Spirit is not the Father,” using the “is” of identity.
c. And “God is the Trinity” and “The Trinity is God” using the “is” of identity.
iii. The burden of proof is on the skeptic to show that the Trinity is a logical contradiction
1. Ask, “Can you explain how the Trinity violates the law of non-contradiction?” Make them bear the burden of proof.
2. Most of the time you will find the skeptic misunderstands the doctrine and ends up attacking a straw man.
a. E.g., the Qur’an quoted above misrepresents the Trinity as three Gods.
b. In discussions with Jehovah’s witnesses and other theological cults you will find they rarely (if ever) accurately represent the doctrine of the Trinity.
i. You can’t disprove the Trinity by showing there is only one God.
ii. You can’t disprove the Trinity by showing that Jesus, the Father, and the Holy Spirit are different Persons.
iii. Why? Because those are both true in the Trinity, and if you acknowledge these two things you have already admitted two of the three lines of evidence for the Trinity.
1. The third line of evidence is that the Father is God, Jesus is God, and the Holy Spirit is God.
V. History of the Trinity
a. Fact: “the elements of the Trinity were understood, accepted, and taught very early in the history of the church.”
b. First Century
i. The New Testament
1. As Scripture this is our starting point and basis for our beliefs
2. This is where the doctrine of the Trinity originates, even if a more precise formulation developed over time
a. In other words, if Scripture teaches the elements of the Trinity, then Scripture teaches the elements of the Trinity, end of discussion.
b. And if that is the case, it cannot be dismissed as “a fourth century invention” (see below under “Objections”)
3. Sometimes Christians forget the fact that the New Testament is actually 27 separate historical documents.
a. In other words, the New Testament is not just “one witness” to the doctrine of the Trinity.
b. Rather, the multiple writers of the multiple New Testament documents are multiple witnesses to the doctrine of the Trinity.
ii. Less than thirty years passed from the death of Christ before we have written evidence of the Trinitarian formula from Matt. 28:19 being used as a regular baptismal rite.
1. Didache, 35-60 AD
a. “But concerning baptism, thus shall ye baptize. Having first recited all these things, baptize in the name of the Father and of the Son and of the Holy Spirit in living (running) water…But if thou has neither, then pour water on the head thrice in the name of the Father and of the Son and of the Holy Spirit.”
b. “If we are correct above in thinking that an initiatory rite, especially that of baptism, which uses the phrase “in the name” will carry with it a substantial package of teaching, then we may assume that here again we have an intimation of Trinitarian belief in the first century.”
c. Second and Third Century
i. Ignatius (110-130) “We have also as a Physician the Lord our God, Jesus the Christ, the only-begotten Son and Word, before time began, but who afterwards became also man, of Mary the virgin.”
ii. Church historian Irenaeus (115-190) a disciple of Polycarp who was a disciple of the Apostle John, in his Against Heresies X.I, wrote:
1. “…in order that through Christ Jesus, our Lord, and God, and Savior, and King, according to the will of the invisible Father, ‘every knee should bow…’”
iii. Tertullian (160-230) wrote about “a trinity of one divinity, Father, Son, and Holy Spirit.” He also wrote:
1. “Thus the connection of the Father in the Son, and of the Son in the Paraclete, produces three coherent Persons, who are yet distinct One from Another. These Three are one essence, not one Person, as it is said, ‘I and my Father are One,’ in respect of unity of substance, not singularity of number.”
iv. “The concept of Trinity in unity, three distinct persons who are the one God, is then firmly entrenched in Christian thought by the middle to late second century, and has even acquired a special term to refer to it.”
d. Fourth Century
i. Council of Nicea (325 AD)
1. “Athanasius and the Council of Nicea (A.D. 325) argued the consubstantiality of the Father, Son, and Spirit. The Arians viewed the persons as different essence (heteroousios) and unlike (anomoios); Athanasius held that the persons were of one essence, or consubstantial (homoousios).”
ii. Council of Constantinople (381 AD)
1. Developed the formula that the Trinity is “one ousia [essence or substance] in three hupostaseis [subsistences].”
2. “Final acceptance of the Athanasian language of homoousios was made possible by the use of that term in connection with an adequate explanation of the threeness of the Godhead. This was the achievement of the Cappadocian fathers…The Cappadocians argued one ousia but three hypostases, defining hypostasis as a particularization, or an individual instance, of an essence, or ousia. Thus Peter, James, and John are three individual instances, or hypostases, of the essence, or ousia, of humanity. In order to avoid a tritheism of three essentially coequal gods, the Cappadocians further stipulated that the entire divine ousia is indivisibly present in the three hypostases or, more precisely, that the three hypostases are eternally subsistent relations in the one ousia.”
VI. Trinitarian Heresies
i. God is one Person who appears in three different modes or is known by three different names: Father, Son, and Holy Spirit.
1. To put it another way, Jesus is the Father, Son, and Holy Spirit.
2. “They believe instead that God exists and manifests Himself in one form at a time. The Father, the Son, and the Spirit are three distinct but not coexistent persons.”
3. But who then was Jesus praying to in John 17? (see also Matt. 3:15-17)
ii. Also known as Sabellianism after the Roman theologian Sabellius.
iii. E.g., “The Trinity is like a man who has three different roles as husband, father, and son.”
iv. Modern day advocates
1. “Jesus Only” United Oneness Pentecostals
2. T.D. Jakes
b. Tritheism (“three gods”)
i. The three Persons of the Trinity are three separate Gods.
ii. Divides the unified essence into three gods, denying God’s unity.
1. This denies the overwhelming biblical teaching that there is one and only one God.
2. “The orthodox doctrine asserts that the three centers of personhood share one unified divine essence that cannot be separated in essential being or divinity.”
iii. E.g., “The Trinity is like Peter, James and John who are all human in essence.”
iv. Modern day advocates
1. Mormons (though Mormons may be better classified as polytheists or henotheists)
c. “Trinity, therefore, is an attempt to avoid both a monadic oneness and a tritheistic view of God through the affirmation that God is one in essence and three in person.”
a. “The word ‘Trinity’ does not appear in the Bible.”
i. So what? The word “Bible” does not appear in the Bible either.
1. The underlying assumption to this objection is that if a specific word cannot be found in the Bible than the concept that word represents must not be biblical. This is patently false.
2. Ask, “So are you saying that if the word is not found in the Bible it cannot be biblically true?”
a. This is a good question to ask Jehovah’s Witnesses who object to the Trinity on this basis.
b. If the JW says “Yes” then you can simply point out that the word “Jehovah” is not in the Bible nor is the phrase “Watchtower Bible and Tract Society.”
c. If the JW says “No” then ask, “So then why did you raise that objection?”
ii. The question is not “Does this term appear in the Bible?” but rather “Is this doctrine taught in the Bible?”
1. You can call it the “Trinity” or you can call it the “Hokey Pokey” (though this is probably not advisable).
2. What matters is whether or not the doctrine is found in Scripture.
b. “The doctrine of the Trinity was a late development.”
i. As stated above, the doctrine itself is derived from Scripture.
ii. The mistake in trying to post-date the doctrine of the Trinity is in confusing the origin of the doctrine with its later formulation.
iii. Robert Morey notes that the doctrine had to originate early since “In order for the doctrine of the Trinity to be defined and defended against the heretics who were attacking it, it obviously had to already exist.”
iv. In other words, the doctrine comes from Scripture itself while its exact formulation and precise language was something to be worked out by the early church fathers.
1. Remember, the early church fathers had Scripture as their starting point! They looked to Scripture to see what Scripture taught!
2. In applying and using terms such as homoousios, substantia, hypostases, etc., what they sought was very precise, descriptive language in order to:
a. Draw a line between heresy and orthodoxy and…
b. Prevent heretics from (1) affirming orthodox doctrine found in creeds and (2) confusing Christian believers.
3. Councils were called and creeds affirmed largely in reaction to heretics who attempted to challenge orthodoxy.
v. Why the delay?
1. The early church had merely passed on what had been handed down to them: simple truth from the apostolic witness.
2. Six years after the Edict of Milan in 313 the great persecutions under Diocletian and Maximin came to an end, only to be faced with a severe threat from within: Arius began teaching regarding the Word of God that "once He was not."
3. The doctrine of the Trinity was officially formulated when it was directly attacked by the Arians of the early fourth century.
vi. "The adoption of the Nicene Creed in 325 and the Chalcedonian Creed in 451 stabilized the doctrines of the Trinity and Christ for over one thousand years.”
vii. “One might wonder why major controversy over theological questions came so late in the history of the ancient church; but, in the era of persecution, allegiance to Christ and the Scriptures took precedence over the meaning of particular doctrines.”
c. “The Trinity is beyond human comprehension.”
i. Yes, and?
ii. “…while the Trinity doctrine is to some degree mysterious and ultimately incomprehensible to the finite mind, it can be discussed in a meaningful way and it is not an absurdity.”
iii. “To say that the Trinity cannot be understood likewise is imprecise, or at least open to misinterpretation. Trinitarian theologians do not mean to imply that the Trinity is unintelligible nonsense. Rather, the point they are making is that the Trinity cannot be fully fathomed, or comprehended, by the finite mind of a man. There is a difference between gaining a basically correct understanding of something and having a complete, comprehensive, all-embracing, perfect understanding of it. The way many other theologians would express this difference is to say that the Trinity can be understood, or ‘apprehended,’ but not ‘comprehended.’”
iv. “Its complexity is not an argument against its tenability, if anything it is the strongest point in its favor. After all, we are dealing with the nature of the eternal God of the Universe…would it be surprising to us, who are merely mortal, finite creatures, to find that his basic character is incomprehensible?”
VIII. Why does the Trinity matter?
a. “…it reveals What and Who God is (one God in three Persons).”
b. It “brings together in a coherent manner the great truths about God’s historical, redemptive actions.”
i. E.g., the atonement: “The Father thought it, the Son bought it, and the Spirit brought it.”
ii. “Just about everything that matters in Christianity hangs on the truth of God’s three-in-oneness.”
c. Only a God who has plurality within unity can adequately account for God’s being love and for God’s knowing.
i. “…only a God who has plurality within unity can adequately account for God being love and for the use of his divine mind. If God is a single solitary being…then before creation God had no one to love and could not distinguish between the knower and the known (a requisite of self-knowledge). The Trinity doctrine…resolves the philosophical problems inherent in…uncompromising and rigid monotheism.”
“Holy, Holy, Holy, Merciful and Mighty;
God in Three Persons,
 Alan W. Gomes, Unmasking the Cults (Grand Rapids: Zondervan, 1995), 10.
 William G.T. Shedd, Dogmatic Theology, 3rd ed., ed. Alan W. Gomes (Phillipsburg: P&R, 2003), 229.
 Should You Believe in the Trinity? (Brooklyn: Watchtower Bible and Tract Society, 1989), 31.
 Reconciliation (Brooklyn: Watchtower Bible and Tract Society, 1928), 101.
 Sura 5:70
 Sura 5:73
 Thomas Jefferson to Timothy Pickering, February 27, 1821, in The Writings of Thomas Jefferson, vol. 15, ed. Albert Ellery Bergh (Washington, D.C.: Thomas Jefferson Memorial Association, 1907), 323.
 James White, The Forgotten Trinity: Recovering the Heart of Christian Belief (Minneapolis: Bethany House, 1998), 26.
 Section 3c taken from Kenneth Richard Samples, Without a Doubt: Answering the 20 Toughest Faith Questions (Grand Rapids: Baker Books, 2004), 65.
 Richard Muller, Dictionary of Latin and Greek Theological Terms: Drawn Principally from Protestant Scholastic Theology (Grand Rapids: Baker Academic, 1985), 309.
 Shedd, Dogmatic Theology, 50.
 Norman L. Geisler and Abdul Saleeb, Answering Islam: The Crescent in Light of the Cross (Grand Rapids: Baker Books, 2002), 272.
 Section 4c2 adapted from Paul Copan, “That’s Just Your Interpretation”: Responding to Skeptics Who Challenge Your Faith (Grand Rapids: Baker Books, 2001), 123.
 Section 4d adapted from Gregory Koukl, The Trinity: A Solution, Not a Problem (Signal Hill: Stand to Reason, 1994), 7.
 Ibid., 8.
 Koukl, The Trinity, 8.
 J.B. Lightfoot, ed., The Apostolic Fathers (Grand Rapids: Baker, 1976), 126.
 Calvin Beisner, God in Three Persons (Wheaton: Tyndale House, 1984), 47.
 Alexander Roberts and James Donaldson, eds., The Ante-Nicean Fathers (Grand Rapids: Eerdmans, 1975), Vol. I, p. 52, Ephesians 7.
 Roberts and Donaldson, The Ante-Nicean Fathers, Vol. I, 331.
 Ibid., Vol. 4, 9, On Modesty, chap. 21.
 Roberts and Donaldson, The Ante-Nicean Fathers, Vol. 3, p. 621, Against Praxeas, XXV.
 Beisner, God in Three Persons, 54.
 Muller, Dictionary of Latin and Greek Theological Terms, 307.
 Henry W. Holloman, Kregel Dictionary of the Bible and Theology (Grand Rapids: Kregel, 2005), 547.
 Muller, Dictionary of Latin and Greek Theological Terms, 308.
 Holloman, Kregel Dictionary of the Bible and Theology, 550.
 Ibid., 549.
 Muller, Dictionary of Latin and Greek Theological Terms, 307.
 Robert Morey, The Trinity: Evidence and Issues (Grand Rapids: World, 1996), 436.
 Section 7b5 taken from Koukl, The Trinity, 9.
 Harold O.J. Brown, Heresies: Heresy and Orthodoxy in the History of the Church (Grand Rapids: Hendrickson, 1988), 105.
 Earle E. Cairns, Christianity Through the Centuries: A History of the Christian Church, 3rd ed. (Grand Rapids: Zondervan, 1996) , 125-126.
 Samples, Without a Doubt, 72.
 Robert M. Bowman Jr., Why You Should Believe in the Trinity (Grand Rapids: Baker, 1989), 16-17.
 John Gilchrist, Facing the Muslim Challenge (Capetown: Life Challenge Africa, 2002), 66. Gilchrist goes on to say, “One cannot help asking whether a concept of God that can easily be understood in the human mind was not perhaps conceived there in the first place.”
 Samples, Without a Doubt, 74.
 Ibid., 75.
 Bruce Milne, Know the Truth (Downers Grove: InverVarsity, 1982), 62.
 Kenneth Richard Samples, A World of Difference: Putting Christian Truth-Claims to the Worldview Test (Grand Rapids: Baker, 2007), 260-261.