Why is understanding the doctrine of the Trinity so important? Simply because without the Trinity, there would be no Gospel. The Trinity is foundational to our Christian faith.
What is the Gospel? The Scripture defines it the best:
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth, Romans 1:16 (emphasis mine).
The Gospel (from the Greek, euaggelion, meaning 'good news') is the message of the life, death, and resurrection of Jesus. He paid the price for all sin and has reconciled us with God. He offers that salvation freely to those who will believe. This is the Gospel.
Once you were alienated from God ... now he has reconciled you by Christ’s physical body through death to present you holy in his sight, without blemish and free from accusation ... This is the gospel, Colossians 1:21-23 NIV (emphasis mine).
The Gospel is summarized in the most familiar verse in the entire Bible: John 3:16.
The doctrine of the Trinity means that there is one God who eternally exists as three distinct persons — the Father, Son, and Holy Spirit. God is one in essence, yet three in person.
The Father, Son, and Holy Spirit are distinct persons, each Person is fully God, and there is only one God.
In the 4th century, Athanasius, a Christian theologian, wrote: "We worship one God in trinity and the trinity in unity, neither blending their persons nor dividing their essence. For the person of the Father is a distinct person, the person of the Son is another, and that of the Holy Spirit still another. But the divinity of the Father, Son, and Holy Spirit is one, their glory equal, their majesty coeternal."
Is this easy to understand? No.
Is there an easy way to explain it? Not really.
Yet, our Christian faith is hinged to the doctrine of the Trinity. Though we may not fully understand it, in faith we accept it.
However, as we study the Scriptures that relate to the Trinity, understanding will come. With that understanding, we find ourselves growing stronger in our faith.
With the advent of more and more new age invading our culture, more cults, and more perversion of the gospel, we need to be able to stand strong in our faith. Knowing where we stand and what we stand on will keep us from being swayed or double-minded (Jam 1:8).
When someone, such as a Jehovah's Witness, tells you that Jesus wasn't really God because the Trinity isn't mentioned in the Bible, can you counter that? Do you know where the Scriptures are? Or are you just blindly repeating what you've heard at church. If that's the case, it means you'll be unable to help them realize they've been misled and won't be able to minister to them. Worse case, it means you'll be easily swayed.
If we know the truth, deception doesn't stand a chance. Ye shall know the truth, and the truth shall make you free, John 8:32. It's only the truth we know, that will make us free … free from being deceived!
While it's true that the actual word, Trinity (from the Latin, trinitas) is not in the Bible, the concept of the Trinity is throughout the Scriptures.
In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep, Genesis 1:1 (emphasis mine).
God = (h0430) "elôhîym" is actually "Gods" being the plural form of God (h0433) "elôha" meaning God (singular). In Genesis 1:1, "elôhîym" is used grammatically in the singular sense.
The Holy Spirit is involved in creation as well: And the Spirit of God moved upon the face of the waters, Genesis 1:2 (emphasis mine).
God spoke everything into existence with His Word: And God said, Let there be light: and there was light, Genesis 1:3 (emphasis mine).
In John 1:1-3, Jesus is revealed as the Word: In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by him; and without him was not any thing made that was made. Jesus is the Word, as stated here: And the Word was made flesh, John 1:14 (emphasis mine).
God is revealed as God (the Father) who spoke the Word (Jesus) and the Spirit (Holy Ghost) did the work.
There's an interesting change of pronouns when God created man: And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth. So God created man in his own image, in the image of God created he him; male and female created he them, Genesis 1:26-27 (emphasis mine).
Some pronouns are plural and others singular, indicating a plurality, but a unity as well. In our image = in his own image.
So, the very first chapter of the Bible sets the stage for the doctrine of the Trinity. God is revealed in three persons. But, God is also revealed as ONE God: Hear, O Israel: The LORD our God is one LORD, Deuteronomy 6:4 (emphasis mine).
There are various places throughout the Scriptures where the plurality of God is evident.
Here God is speaking to Jesus and/or Holy Spirit:
In 2. Samuel 23:2-3, all three are mentioned as speaking at the same time: The Spirit of the LORD spake by me, and his word was in my tongue. The God of Israel said, the Rock of Israel spake to me. (emphasis mine)
Jesus, the night before His crucifixion, told His disciples that all three, the Holy Spirit, the Father, and He, Jesus, would make their abode with them.
And I will pray the Father, and he shall give you another Comforter, that he may abide with you for ever, John 14:16 (emphasis mine).
Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him, John 14:23 (emphasis mine).
Paul clarifies this by actually naming them: But ye are not in the flesh, but in the Spirit, if so be that the Spirit of God dwell in you. Now if any man have not the Spirit of Christ, he is none of his ... But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you, Romans 8:9-11 (emphasis mine).
Yet in Ephesians 4:4, Paul states that there is only one Spirit: There is one body, and one Spirit, even as ye are called in one hope of your calling. (emphasis mine)
Jesus clearly stated that baptism was in the NAME (singular) not names (plural) when He said: Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost, Matthew 28:19 (emphasis mine).
Paul grouped all three together: The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all, 2 Corinthians 13:14.
John also groups them together and then states clearly that these three are one: For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one, 1 John 5:7 (emphasis mine).
Searches the heart of man:
As First and Last (only one can be first and only one can be last!)
We are the temple of God:
The voice of the Lord in the Old Testament is attributed to the Holy Spirit by Paul in the New Testament.
Paul also declared:
Peter told Ananias that lying to the Holy Ghost is lying to God.
For further insight into the Holy Spirit, see What is the role of the Holy Spirit?
As you study the above scriptures, allow the Holy Spirit to lead you into all truth (John 16:13), and may ... The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Ghost, be with you all. Amen, 2 Corinthians 13:14.
Unless stated otherwise, all Bible passages quoted in blue are from the KJV translation.