One of the most misunderstood concepts is the doctrine of the Trinity. Some Christians embrace it, while others revile it. Some see it as Biblical while others see it as heretical. However, it is important to understand as the doctrine of the Trinity has extensive life application. Therefore, a Bible study of the Trinity is important to see what God says about it.
What is the doctrine of the Trinity?
The doctrine of the Trinity is the concept that the Father, Son, and Holy Spirit  are found in one God. Throughout the ages, many counsels, courts, and creeds have acknowledged the Trinity. This has led many to embrace it because their church or denomination embraces it. At the same time, this has also led many to reject it because denominations that have historically embraced it have often been responsible for many abuses and heretical doctrines. However, the Bible is full of references in the Old and New Testaments about it.
How can the Father, Son, and Holy Spirit be one God?
To answer this, we have to look at the Father, Son, and Holy Spirit and compare them with one another to see where each fits into one God. The first thing to consider is that the Bible teaches that each member of the Trinity of God is a person that coexists with the others and interacts with creation. There are many proof texts that demonstrate the Trinity, but the most direct proof text can be found in 1 John 5:7 in the King James Bible as follows: “For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.” (Many Bibles use corrupted Greek manuscripts discovered in the mid-1800s that do not have 1 John 5:7. These Bibles then split 1 John 5:8 to create a new 1 John 5:7-8.)
The Bible says that God is a spirit (John 4:24). God is not made of the elements of creation, which enables Him to have more attributes and boundless abilities than a created being. However, God is also a person in His attributes to help us understand God’s thoughts toward us and how He works in our lives. Understanding God by His human attributes is called anthropomorphism. Some of these attributes are:
- He creates (Genesis 1:1)
- He destroys, as seen with Sodom and Gomorrah (Genesis 18 and 19)
- He provides (Psalm 104:27- 30)
- He cares (1 Peter 5:6-7)
- He hears (Psalm 94:9-10)
- He hates (Proverbs 6:16)
- He grieves (Genesis 6:6; Ephesians 4:30) and
- He loves (John 3:16; Romans 5:8).
In addition to being a person, the Bible makes numerous references to God as a singular being with plural roles and manifestations. God can exist in the plural sense of His person-hood all the while containing Himself to a singular form of God (Genesis 1:26; Genesis 3:22; Genesis 11:7; and Isaiah 6:8). The Hebrew word for God in the first two examples is the word, Elohim (el-o-heem), which is used over 2000 times in the Bible. Elohim is a reference to God’s title. However, it is a plural noun. In English, plural means two or more, but in Hebrew plural denotes three or more. Critics of this fact refuse to acknowledge that God can present Himself in three different persons because He is not limited to time or space (Psalms 90:4; Psalms 139:6-12; Jeremiah 23:24; 2 Peter 3:8; Revelation 1:8, 19). They do not take into account the context of which person of the Trinity is involved in parts of a passage either. An example often argued is in Genesis 1:27 where they claim Elohim is singular because the words His and Him are singular – “So God (Elohim) created man in His own image, in the image of God (Elohim) created He him; male and female created He them.” This verse demonstrates that man was created in His own image (Christ as creator) and man was created in the image of God with a spirit (Zechariah 12:1; John 1:1-4, 14). The following examples demonstrate the Trinity of persons in one God:
- The LORD (Jehovah) refers to Himself as the Son that will be crucified (Zechariah 12:10)
- The LORD (Jehovah) says that He is the only God (Elohim) and Savior (Isaiah 43:10-11; Isaiah 45:11-22)
- A prophecy of Jesus refers to Him as God, God the Father, and Counsellor (Isaiah 9:6; Micah 5:2)
- A prophecy of Jesus refers to Him as Immanuel, which means “God with us” (Isaiah 7:14-16; Matthew 1:21-25)
- A prophecy of Jesus mentions the seven manifestations of the Holy Spirit, of which one is the Spirit of Counsel making Jesus the Counselor. The word for counsel (esa) as part of the Spirit in Isaiah 11:1 is from the same root as the word counsellor (yaas) describing Jesus in Isaiah 9:6. (See also Revelation 1:4; Revelation 3:1; Revelation 5:6)
- The Word was with God and is God and the Word is God the Son (John 1:1; John 1:14)
- Jesus and the Father are one (Mark 2:5-12; John 5:18; John 8:56-59; John 10:30-38; John 14:6-14; 1 John 1:1-4)
- Jesus, the Father, and the Holy Spirit are one and live in the believer as God (Matthew 10:16-20; John 14:15-21; John 15:26-27; Romans 8:9-11; Galatians 3:13-22; Philippians 1:19-20)
- The Spirit of Christ that testified to the Old Testament prophets that Christ would suffer and die was also the Holy Spirit that was promised and given to the Apostles (Isaiah 53; Jeremiah 31:33; Zechariah 12:1; Luke 11:13; Acts 1:4; Acts 2:1-4; Acts 2:25-36; Galatians 2:18-22; Galatians 4:6; 1 Peter 1:9-12)
There are literally hundreds more of these types of examples, not counting the different Hebrew names for God used in these verses that indicate His different roles as provider, redeemer, etc.
What is the practical importance of the Trinity?
Finally, it is important to recognize each person in the Trinity in God’s interaction with us and creation. An example of this is found concerning prayer in Romans 8:26-28 (KJV):
Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered. And he that searcheth the hearts knoweth what is the mind of the Spirit, because he maketh intercession for the saints according to the will of God. And we know that all things work together for good to them that love God, to them who are the called according to his purpose.
These verses tell us that God the Holy Spirit helps is when we do not know what to pray for in times of trouble. The Spirit makes intercession  or communicates on our behalf for us in a language that cannot be spoken by humans. The intercession is received by “he that searches the hearts.” He that searches the hearts is the Word of God (Luke 2:35; Ephesians 6:17; Hebrews 4:12). The Word of God is Jesus Christ who knows the mind of the Spirit (John 1:1, 14; Colossian 3:16; 1 Thessalonian 2:13; 1 John 2:14). The Word of God, Christ, makes intercession for us according to the will of God, the Father. We know it is God the Father because in Romans 8:28-32 we are told that we are called according to God’s purpose and He predestinated us to be conformed to the image of His Son, Whom He did not spare and allowed Him to be crucified for us. Knowing that each person of the Trinity has a role, even in our prayers, gives us hope. Hope in the knowledge that God as the Father, Son, and Holy Spirit all had a part in our salvation, deliverance, and victory over all things from eternity past to eternity future because He loves us (Romans 8:33-39).
The doctrine of the Trinity is the concept that the Father, Son, and Holy Spirit are found in one God. The Bible teaches that God is a spirit, yet He interacts with creation in the three persons of the Father, Son, and Holy Spirit. Knowing that each person of the Trinity has a role, even in our prayers, gives us hope of our salvation, deliverance from sin, and victory over all things.
More for you to read: How Can We Recognize False Doctrines? 
Resources – Scripture quotations are from The Holy Bible, King James Version. Williams, Michael, (2013). Bible Doctrines. Albuquerque, NM: Selah Mountain Bible Institute. (1) The Interactive Bible. (2015). “Trinity: plural references to God in the Old Testament”. Retrieved from: http://www.bible.ca/trinity/trinity-oneness-unity-plural-nouns-pronouns-verbs-adverbs.htm