A Doctrinal Overview
Christianity is, at its core, Trinitarian in nature. In other words, the doctrine of the Trinity is central to the Christian faith and life. Remove the Trinity and you remove the beating heart from the body that is the Church.
So, briefly stated, what is the doctrine of the Trinity? The doctrine of the Trinity is the teaching that there is one God who exists in three distinct, yet co-equal and co-eternal Persons (Father, Son, and Holy Spirit). Put another way, there is one Being of God and three Persons of God. We must be careful, however, not to understand this as meaning there are three gods (i.e. Tritheism), which is to divide the essence or substance of God, nor are we to think that there is one person of God who manifests Himself in three different ways: sometimes as the Father, sometimes as the Son, and sometimes as the Spirit. This latter notion is known as Modalism. Both Tritheism and Modalism are heretical doctrines that the Church has historically rejected as being contrary to Scripture.
Following is the Athanasian Creed (ca AD 500), which was not actually written by Athanasius. It was, however, attributed to him for a time, and therefore the name stuck. The creed is a stalwart articulation of this most majestic doctrine. While it may be lengthy, it will be a blessing to the soul who diligently reads it:
Whosoever will be saved, before all things it is necessary that he hold the catholic [i.e. universal and historic, not Roman Catholic] faith. Which faith except everyone do keep whole and undefiled, without doubt he shall perish everlastingly. And the catholic faith is this: That we worship one God in Trinity, and Trinity in Unity, neither confounding the persons, nor dividing the substance.
For there is one Person of the Father, another of the Son, and another of the Holy Spirit. But the Godhead of the Father, of the Son, and of the Holy Spirit, is all one, the glory equal, the majesty co-eternal.
Such as the Father is, such is the Son, and such is the Holy Spirit. The Father uncreated, the Son uncreated, and the Holy Spirit uncreated. The Father incomprehensible, the Son incomprehensible, and the Holy Spirit incomprehensible.
The Father eternal, the Son eternal, and the Holy Spirit eternal. And yet they are not three eternals, but one Eternal.
As also there are not three incomprehensibles, nor three uncreated, but one Uncreated, and one Incomprehensible. So likewise the Father is Almighty, the Son Almighty, and the Holy Spirit Almighty. And yet they are not three almighties, but one Almighty.
So the Father is God, the Son is God, and the Holy Spirit is God. And yet they are not three gods, but one God.
So likewise the Father is Lord, the Son Lord, and the Holy Spirit Lord. And yet not three lords, but one Lord.
For as we are compelled by the Christian verity [or truth] to acknowledge each Person by Himself to be both God and Lord, so we are also forbidden by the catholic religion to say that there are three gods or three lords.
The Father is made of none, neither created, nor begotten. The Son is of the Father alone, not made, nor created, but begotten. The Holy Spirit is of the Father, neither made, nor created, nor begotten, but proceeding.
So there is one Father, not three fathers; one Son, not three sons; one Holy Spirit, not three holy spirits.
And in the Trinity none is before or after another; none is greater or less than another, but all three Persons are co-eternal together and co-equal. So that in all things, as is aforesaid, the Unity in Trinity and the Trinity in Unity is to be worshipped.
He therefore that will be saved must think thus of the Trinity.
Furthermore, it is necessary to everlasting salvation that he also believe rightly the Incarnation of our Lord Jesus Christ. For the right faith is, that we believe and confess, that our Lord Jesus Christ, the Son of God, is God and man; God, of the substance of the Father, begotten before the worlds; and man of the substance of his mother, born in the world; perfect God and perfect man, of a rational soul and human flesh subsisting. Equal to the Father, as touching His Godhead; and inferior to the Father, as touching His manhood; who, although He is God and man, yet he is not two, but one Christ; one, not by conversion of the Godhead into flesh [the man Jesus did not take on Divinity] but by taking of the manhood into God [the eternal Son took on human nature]; one altogether; not by confusion [or mixture] of substance, but by unity of person. For as the rational soul and flesh is one man, so God and man is one Christ; who suffered for our salvation, descended into hell [the abode of the dead], rose again the third day from the dead. He ascended into heaven, He sits at the right hand of the Father, God Almighty, from whence He will come to judge the quick and the dead. At His coming all men will rise again with their bodies and shall give account for their own works. And they that have done good shall go into life everlasting; and they that have done evil into everlasting fire.
This is the catholic faith, which except a man believe faithfully, he cannot be saved.
The Doctrine Revealed
Now, while it is true that the Trinity is by far more clearly evidenced in the New Testament than in the Old Testament, as the revelation of the Persons in Unity became clearer through the acts of God in providence, to include redemption, this does not mean evidence is altogether lacking in the Old Testament. For instance, God uses the plural “Us” and “Our” in Genesis 1:26 with reference to man being made in God’s image, according to His likeness. This plurality cannot refer to the angelic host, for man is not said to be made in the image of angels, who themselves are creatures, but of God alone. While some have suggested the plurality here may be understood as referring to a plurality of majesty, such as a king using “we” in reference to himself, I think it is more likely that we see a glimpse of Trinitarian communion in this text. Other such Scriptures give evidence of the Trinity (Gen. 1:2; Ps. 2:7 (cf. Heb. 1:5-6); 33:6; 45:6-7 (cf. Heb. 1:8); 110:1; Isa. 48:16; 61:1 (cf. Lk. 4:16-18); 63:10-11). Louis Berkhof supplies an excellent analysis of this progressive revelation:
The Old Testament does not contain a full revelation of the Trinitarian existence of God, but does contain several indications of it. And this is exactly what might be expected. The Bible never deals with the doctrine of the Trinity as an abstract truth, but reveals the Trinitarian life in its various relations as a living reality, to a certain extent in connection with the works of creation and providence, but particularly in relation to the work of redemption. Its most fundamental revelation is a revelation given in facts rather than in words. And this revelation increases in clarity in the measure in which the redemptivework of God is more clearly revealed, as in the incarnation of the Son and the outpouring of the Holy Spirit. And the more the glorious reality of the Trinity stands out in the facts of history, the clearer the statements of the doctrine become. The fuller revelation of the Trinity in the New Testament is due to the fact that the Word became flesh, and that the Holy Spirit took up His abode in the Church.
In other words, the doctrine of the Trinity, due to its primary revelation in facts/acts, is intricately tied to the progress of redemption. This does not mean, however, that God did not reveal His Trinitarian nature in the Old Testament, as has already been briefly addressed. But it does mean that, as redemptive history progressed, so too the clarity of the Trinity progressed. It is as Craig Carter says, on a similar note, “The christological meaning of an Old Testament text could be discerned on this side of the resurrection because it was always there in the text, even though it was not necessarily discerned (or at least not clearly discerned) by those who lived before the incarnation of God in Christ.” It is easy to understand, therefore, as to why the New Testament is more abundant in its teaching on this doctrine. With the fuller revelation of God’s redemptive purpose in Christ comes a fuller revelation of the three Persons’ roles in salvation (Eph. 1:3-14).
A Scriptural Compilation
The following is a compilation of select New Testament Scriptures that show forth this teaching of the Trinity. Some texts only speak of two Persons within the Trinity, whereas others speak of all three. You will note that these passages present the three Persons of the Godhead (Father, Son, and Holy Spirit) as distinct, yet equal in nature/essence. These passages reveal to us the importance of this doctrine in relation to the Christian faith and life (e.g. salvation, baptism, prayer, worship). As you read through these texts, ask yourself these questions: How do the Father, the Son, and the Holy Spirit relate to one another? What are their distinct roles? What aspect of the Christian faith/life does this text relate to?
John 1:1-5, 14, 18 “In the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through Him, and without Him nothing was made that was made. In Him was life, and the life was the light of men. And the light shines in the darkness, and the darkness did not comprehend it…. And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth…. No one has seen God at any time. The only begotten Son, who is in the bosom of the Father, He has declared Him.”
Matthew 28:19 “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit.”
Acts 2:33, 36 “Therefore being exalted to the right hand of God, and having received from the Father the promise of the Holy Spirit, He poured out this which you now see and hear…. Therefore let all the house of Israel know assuredly that God has made this Jesus, whom you crucified, both Lord and Christ.”
Romans 8:1-4 “There is therefore now no condemnation to those who are in Christ Jesus, who do not walk according to the flesh, but according to the Spirit. For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death. For what the law could not do in that it was weak through the flesh, God did by sending His own Son in the likeness of sinful flesh on account of sin: He condemned sin in the flesh, that the righteous requirement of the law might be fulfilled in us who do not walk according to the flesh but according to the Spirit.”
Romans 14:17-18 “for the kingdom of God is not eating and drinking, but righteousness and peace and joy in the Holy Spirit. For he who serves Christ in these things is acceptable to God and approved by men.”
Romans 15:30 “Now I beg you, brethren, through the Lord Jesus Christ, and through the love of the Spirit, that you strive together with me in prayers to God for me.”
1 Corinthians 12:4-6 “There are diversities of gifts, but the same Spirit. There are differences of ministries, but the same Lord. And there are diversities of activities, but it is the same God who works all in all.”
2 Corinthians 13:14 “The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all. Amen.”
Galatians 4:6 “And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, ‘Abba, Father!’’
Ephesians 1:3-7, 13-14 “Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ, just as He chose us in Him before the foundation of the world, that we should be holy and without blame before Him in love, having predestined us to adoption as sons by Jesus Christ to Himself, according to the good pleasure of His will, to the praise of the glory of His grace, by which He made us accepted in the Beloved. In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace…. In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also having believed, you were sealed with the Holy Spirit of promise, who is the guarantee of our inheritance until the redemption of the purchased possession, to the praise of His glory.”
Ephesians 4:4-6 “There is one body and one Spirit, just as you were called in one hope of your calling; one Lord, one faith, one baptism; one God and Father of all, who is above all, and through all, and in you all.”
Philippians 3:3 “For we are the [true] circumcision, who worship God in the Spirit, rejoice in Christ Jesus, and have no confidence in the flesh.”
1 Thessalonians 4:7-8 “For God did not call us to uncleanness, but in holiness. Therefore he who rejects this does not reject man, but God, who has also given us His Holy Spirit.”
2 Thessalonians 2:13-14 “But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth, to which He called you by our gospel, for the obtaining of the glory of our Lord Jesus Christ.”
Titus 3:4-7 “But when the kindness and the love of God our Savior toward man appeared, not by works of righteousness which we have done, but according to His mercy He saved us, through the washing of regeneration and renewing of the Holy Spirit, whom He poured out on us abundantly through Jesus Christ our Savior, that having been justified by His grace we should become heirs according to the hope of eternal life.”
Hebrews 1:1-3 “God, who at various times and in various ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds: who being the brightness of His glory and the express image of His person and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high.”
Hebrews 9:14 “how much more shall the blood of Christ, who through the eternal Spirit offered Himself without spot to God, cleanse your conscience from dead works to serve the living God?”
1 Peter 1:2 “elect according to the foreknowledge of God the Father, in sanctification of the Spirit, for obedience and sprinkling of the blood of Jesus Christ.”
1 Peter 3:18 “For Christ also suffered once for sins, the just for the unjust, that He might bring us to God, being put to death in the flesh but made alive by the Spirit.”
1 John 5:20 “And we know that the Son of God has come and has given us an understanding, that we may know Him who is true; and we are in Him who is true, in His Son Jesus Christ. This is the true God and eternal life.”
A Theological Summary
Hopefully you have recognized some key areas in the Christian life where the triune nature and relationship of the Father, Son, and Holy Spirit play a vital role. Indeed, it is impossible to talk about the Christian faith and life without bringing into the discussion the triune nature of God (whether we realize it or not). So, following are a few summary points, based on the above passages, on the significance of the Trinity in our lives.
Salvation: The Father chooses or adopts His people; the Son secures their redemption by His life and bloody substitutionary sacrifice; and the Holy Spirit applies the work of Christ’s redemption in the regeneration, sanctification, and glorification of the elect.
Worship: Worship and praise is due to the Father, the Son, and the Holy Spirit, although the Scriptures typically present worship as being offered to the Father, through the Son (e.g. in His name), and in the fellowship and power of the Spirit. We worship the Triune God!
Prayer: We pray to the Father, in the name of Jesus Christ (i.e. He mediates for us), and in the power and guidance of the Spirit.
We looked at twenty New Testament Scripture passages above, demonstrating the biblical teaching of the Trinity and its significance for the Christian faith and life. Hopefully, you noticed the equality of nature between the Persons of the Trinity. You should have also noticed the different roles of each Person, especially with regard to salvation. You should have also noticed the revelatory significance of the Son and Spirit to the Father; that is, they reveal and bring us to the Father. You should have also picked up on the shared titles between the Father and the Son (i.e. Lord, Savior).
What this study has demonstrated is that Christianity is fundamentally Trinitarian in nature. The doctrine of the Trinity is central and essential to our faith and life. For this reason, we should be thoroughly grounded in and convinced of this glorious doctrine.
 Louis Berkhof, Systematic Theology (MI: Eerdmans, 1932), 85. Emphasis added.
 Craig A. Carter, Interpreting Scripture with the Great Tradition (MI: Baker Academic, 2018), xvi.
 All Scripture quotations are from the NKJV.
 Keep in mind that “God” in Scripture most often refers to the Father. However, in Titus 2:13 and 2 Peter 1:1 “God” refers to Jesus Christ. Note also Acts 5:3-4 where lying to the Holy Spirit is lying to God.
 Verse 18 contains a textual variant. The NASB, for example, says “the only begotten God”. The NASB is based on earlier manuscript evidence. This alone, however, does not mean the original read “God” rather than “Son”. The truth is there’s strong debating points on both sides. Both have external evidences they can point to, to include quotations from early Church Fathers. For instance, Irenaeus and Clement used both renderings. Additionally, both sides can make strong arguments from the internal evidence (the usage and consistency within the text itself), although I think this aspect is more favorable to the reading of “Son”. Either way, the theological understanding is consistent with biblical doctrine in general and the doctrine of the Trinity in particular.