The Trinity is the biblical concept that God exists as three Divine Persons – the Father, the Son, and the Holy Spirit. The purpose of this article is not to be a comprehensive study of the doctrine of the Trinity. The basic goals of this article are 1) to point you to some of the key Scriptures which reveal the truth of the Trinity and 2) to briefly discuss why it is important to affirm this doctrine.
What is the Trinity? One of the clearest meaning of the Trinity can be found in the Belgic Confession, written in 1559, which defines the Trinity, “According to this truth and this Word of God, we believe in one only God, who is one single essence, in which are three persons, really, truly, and eternally distinct, according to their incommunicable properties; namely, the Father, the Son, and the Holy Ghost (Belgic Confession Article 8).”
This is a concept that can be defined simply, but not something we can truly comprehend because nothing is truly like it in this world. The minute we say, “the Trinity is like…”, we start to speak in error because the Trinity is not like anything else.
Is It Biblical?
There are groups who deny the truth of the Trinity. The most common argument of these groups is that the word “Trinity” is not used in the Bible. This is true; however, just because the word is not used does not mean it is not taught in the Bible.
To give an example of this concept, we can look at Exodus 25 where God tells Moses how the Ark of the Covenant is to be built. Its length should be 45 inches long, 27 inches wide and 27 inches tall (Exodus 25:10). In other words, it could be described as a rectangular box. The actual words “rectangle” and “box” do not appear in the text, but it does not mean we are describing the Ark in an unbiblical or heretical way. We are simply drawing the conclusion that based on the specific details God does record in the Bible that the Ark was a rectangular box.
As John Piper puts it when describing the word providence (also not in most English translations), “what matters is that we grasp truly what a writer or speaker intends to communicate with his words.” 
Just like we draw the conclusion that the Ark was a rectangular box based on the Bible, we draw the conclusion that God exists as three Persons based on the Bible. There are several places throughout Scripture where this is illustrated but for this article, we will focus on some of the areas in which the Bible assigns divine attributes to each person of the Trinity. 
Divine names and titles are given to all three Persons. Paul begins most of his letters with a greeting of “God our Father”, such as in Romans 1:7. He does the same for Jesus when he calls Him, “Christ who is God over all, blessed forever (Romans 9:5).” John also says that “the Word was God (John 1:1).” He later clarifies that the Word became flesh and then identified the Word as Jesus (John 1:14, 17). Finally, in Acts 5:3-4 we see where lying to the Holy Spirit is the same as lying to God. It is clear from these passages that the divine name and title of God are given to all three Persons.
The Scriptures show that divine attributes – those attributes that only God has – are assigned to all three Persons. The attribute of eternality means that something has always existed and will never cease to exist. The writer to the Hebrews speaks of the Holy Spirit as the “eternal Spirit (Hebrews 9:14)”, showing the Holy Spirit possesses this attribute. Jesus said of Himself that, “I am with you always, until the end of the age (Matthew 28:20).” This affirms Jesus’ eternality as well.
The attribute of omnipresence means the ability to be in all places at all times. In Psalm 139:7, David attributes this to the Holy Spirit when he says to God, “Where shall I go from your Spirit? Or where shall I flee from your presence?” Jesus also says of Himself that He, “searches mind and heart (Revelation 2:23)”, showing that He is omniscient as well.
No human has even one of the divine attributes.
In Isaiah 42:8, it is said by God, “I am the Lord; that is my name; my glory I give to no other, nor my praise to carved idols.” Jesus, however, insisted that He receive honor just as God the Father does when He said, “The Father judges no one, but has given all judgment to the Son, that all may honor the Son, just as they honor the Father. Whoever does not honor the Son does not honor the Father who has sent him (John 5:22-23).” In Romans 9:1, Paul swears by the Holy Spirit and Jesus says that the unforgivable sin is blasphemy against the Holy Spirit.
Finally, when the resurrected Jesus appeared to His disciples and gave them the great commission, He told them to baptize, “in the name of the Father and of the Son and of the Holy Spirit (Matthew 28:19).” Similarly, there are many Trinitarian benedictions given in the epistles, such as 2 Corinthians 13:14, “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.”
This is just a small sample of verses among many, but it is clear that in the Old Testament and the New, the Gospels, Acts and the Epistles, that the writers give divine titles, attributes and honor to God the Father, Son, and Holy Spirit. Like we draw the conclusion that Ark was a rectangle based on the attributes given to it, so we can determine the triune nature of God based on how the Bible speaks of each Person.
Why Is This Important
Theologian Herman Bavinck said, if God were only in heaven, we would begin to think of God as “distant and removed and to think of self and world as independent of God.” Similarly, he said, if God was only here in this world, we would “draw God down into the world, to identify Him with all the world, and so to deify the self and the world.” 
Because the Bible speaks of God as three distinct persons, we know that God the Father is in heaven in unapproachable holiness, that Jesus is also in heaven interceding on our behalf and also able to identify with us since He lived among us and that the Holy Spirit dwells in us right now, leading us in sanctification.
This is a great blessing to know that God is both perfect and not confined to this world, but at the same time relates to us and dwells within us.
John Piper, Providence (Wheaton, IL: Crossway, 2020), 32. ↩︎
Much of the next three sections are summarized from Terry L. Jonson, The Identity and Attributes of God (Edinburgh: Banner of Truth, 2019), 33-35 ↩︎
Herman Bavinck, The Wonderful Works of God (Glenside, PA: Westminster Seminary Press, 2019), 142. ↩︎