Today has been deemed Trinity Sunday. One of the marks of Christian orthodoxy is a belief of this doctrine which many outside of Christian Orthodoxy do not hold and out right disavow. In fact, if you go to the website of the Jehovah’s witnesses, an article asks, “Should you believe in the Trinity” (https://www.jw.org/en/library/magazines/g201308/trinity/). Like other monotheistic religions such as Judaism and Islam, they are quick to assert that the doctrine of the Trinity is a myth and that “the statement that there are three persons in one God cannot be found anywhere in the Bible” (https://www.jw.org/en/library/magazines/wp20091101/myth-god-is-a-trinity/). But let’s look at what the Bible does say about this central doctrine of Christianity.

I. God is one.

A. The Old Testament affirms the oneness of God

1. God begins His self revelation to Israel at Sinai saying, I am the Lord Your God…You shall have no other gods before me (Exod 20:2-3, Isa 44:6; Zech 14:9)

2. God is the only God and Savior (Isa 43:10-11)

3. The “Shema” (Deut 6:4)

a. There is only one God

b. God is the LORD, “Yahweh,” the God of Israel.

B. The New Testament affirms the oneness of God

1. Jesus reaffirms the Shema of Deut 6:4 (Mark 12:29)

2. God is one and because of this, the way of salvation is the same for everyone. (Rom 3:29-30)

3. Paul declares that there is but one God and that pagan idols are nothing even though called “gods” (1 Cor 8:4-6).

4. Paul again affirms that God is one and that salvation is only through the one mediator, the man Christ Jesus (1 Tim 2:3-5).

5. James commends the person who believes that God is one, but stresses that intellectual assent to this does not save anyone since even the devils give this assent to the truth of monotheism (James 2:19).

II. There are Three Who are God.

A. Old Testament Support for God’s Plurality

1. In all of the following passages, singular and plural forms are used together.

2. Furthermore, Isaiah presents some more intriguing statements about the plurality of God.

a. The Spirit of the Lord will rest on Messiah, the shoot from the stem of Jesse. Isa 11:1-2

b. The Lord predicts that His Spirit will be upon His Servant the Messiah. Isa 42:1

c. The Messiah is speaking and declares that the Lord God has sent Him, and His Spirit. Isa 42:1

d. The Messiah declares that the Spirit of the Lord God is upon Him, because the Lord has anointed Him to bring good news. Isa 61:1

These passages in Isaiah present three divine persons: the Lord, the Lord’s Spirit, and the Messiah, who is divine (Psa. 110:1)

B. New Testament Support for God’s Plurality

1. The Father

a. The heavenly Father is God. (Matthew 6:26, 30)

b. Paul states that our Father is God. (Rom 1:7)

c. Paul states that there is only one God, the Father. (1 Cor 8:6)

d. Peter states that the Father of the Lord Jesus Christ is God (1 Peter 1:3)

2. What about the Son?

a. The Word, Jesus Christ (v. 14-17), is God (John 1:1)

b. Thomas calls Jesus “my Lord and my God.” (John 20:28)

c. Christ is over all, God blessed forever (Rom 9:5)

d. Jesus Christ is “our great God and Savior” (Titus 2:13)

e. The Father says of the Son, “Your throne, O God, is forever and ever.” (Heb 1:8)

f. Jesus Christ is “our God and Savior.” (2 Peter 1:1)

g. God’s Son, Jesus Christ, is “the true God and eternal life.” (1 John 5:20)

3. What about the Holy Spirit?

a. To lie to the Holy Spirit is to lie to God (Acts 5:3-4)

b. To have the Spirit dwelling in you is to have God dwelling in you. (1 Cor 3:16, 19)

c. To be gifted by the Spirit is to be gifted by God. (1 Cor 12:6, 11)

d. To be born of the Spirit is to be born of God (John 1:13; 3:8)

III. These three equally are the one God

Consider prominent Trinitarian formulae found throughout the New Testament

A. We are to baptize “in the name (singular) of the Father, Son, and Holy Spirit.”

B. Paul urges the brethren by the Lord Jesus Christ and the love of the Spirit to strive in prayers to God. (Rom 15:30)

C. We read of the same Spirit … same Lord … same God. (1 Cor 12:4-6)

D. 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)

E. There is “one Spirit … one Lord … one God and Father. (Eph 4:4-6)

F. Paul says that “we should give thanks to God for you, beloved by the Lord, because God has chosen you … for salvation through sanctification by the Spirit.” (2 Thess 2:13)

G. Peter says we were chosen “according to the foreknowledge of God the Father, by the sanctifying work of the Spirit, that you may obey Jesus Christ.” (1 Peter 1:2)

H. Jude says we are to pray “in the Holy Spirit,” keep ourselves in “the love of God,” and wait “for the mercy of our Lord Jesus Christ to eternal life.” (Jude 20-21)

IV. Definition of the Trinity

There is only one true God, but in the unity of the Godhead there are three co-eternal and co-equal Persons, the same in essence (οὐσία) but distinct in necessary existence (πρόσωπον).

A. God is one, not three Gods, not several, but one.

B. Father, Son, and Spirit are distinct divine Persons.

C. The three Persons of the Trinity are co-eternal and co-equal.

D. The three Persons are distinct in function.

E. The Trinity is incomprehensible.

The doctrine of the Trinity does not assert that God is both three persons and one person at the same time and in exactly the same way. Rather, the doctrine of the Trinity states that three persons share eternally and equally one divine essence or nature. So, in one sense God is one (one essence of God, Heb 1:3), and in an entirely different sense God is three (three persons who are God, Matt 28:19)

He is a Trinity, a unity of equal Persons eternally existing as the one true God.

V. So why is it so important?

First, the atonement is at stake. If Jesus is merely a created being, and not fully God, then it is hard to see how he, a creature, could bear the full wrath of God against all of our sins. Could any creature, no matter how great, really save us?

Second, justification by faith alone is threatened if we deny the full deity of the Son. (This is seen today in the teaching of the Jehovah’s Witnesses, who do not believe in justification by faith alone.) If Jesus is not fully God, we would rightly doubt whether we can really trust him to save us completely. Could we really depend on any creature fully for our salvation?

Third, if Jesus is not infinite God, should we pray to him or worship him? Who but an infinite, omniscient God could hear and respond to all the prayers of all God’s people? And who but God himself is worthy of worship? Indeed, if Jesus is merely a creature, no matter how great, it would be idolatry to worship him—yet the New Testament commands us to do so (Phil 2:9–11; Rev 5:12–14).

Fourth, if someone teaches that Christ was a created being but nonetheless one who saved us, then this teaching wrongly begins to attribute credit for salvation to a creature and not to God himself. But this wrongfully exalts the creature rather than the Creator, something Scripture never allows us to do.

Fifth, the independence and personal nature of God are at stake: If there is no Trinity, then there were no interpersonal relationships within the being of God before creation, and, without personal relationships, it is difficult to see how God could be genuinely personal or be without the need for a creation to relate to.

Sixth, the unity of the universe is at stake: If there is not perfect plurality and perfect unity in God himself, then we have no basis for thinking there can be any ultimate unity among the diverse elements of the universe either.