The Bible clearly teaches that there is only one God (Deuteronomy 6:4; Isaiah 43:11; 44:6; Mark 12:29; 1 Corinthians 8:4; Ephesians 4:6; Timothy 2:5). At the same time, the Bible plainly indicates a plurality within God's nature, consisting of three eternal and coequal persons: the Father, the Son, and the Holy Spirit, each the same in basic nature, but distinct in existence.
Although the word Trinity does not appear in the Bible, the doctrine of the Trinity is a factual conclusion, reached by comparing and combining relevant scriptural truths. "We are setting these truths forth in words not taught by human wisdom but taught by the Holy Spirit, combining and interpreting spiritual truths with spiritual language [to those who possess the Holy Spirit]" (1 Corinthians 2:13 AMPLIFIED).
ONE OF THE BIBLE'S GREAT MYSTERIES
The Trinity is one of the great mysteries of the Bible that cannot be fathomed by the finite mind. Yet, if God were small enough to figure out, He wouldn't be big enough to worship. The Bible tells us that God's thoughts are not our thoughts, nor are His ways our ways (Isaiah 55:8-9). Though we will never fully understand the doctrine of the Trinity, there is no reasonable doubt that it is clearly taught in the Bible.
THE FATHER IS GOD
The Bible teaches that God is all-knowing (Job 37:16; Romans 11:33), all-powerful (Genesis 1:1-3; Job 42:2), all-present (Psalm 139:7-12), eternal (Exodus 3:4; Revelation 1:8), unchangeable (Malachi 3:6; James 1:17), holy (Isaiah 57:15; 1 Peter 1:15-16), righteous and just (Psalm 116:5), merciful and gracious (Psalm 103:8), and able to forgive sin (Exodus 34:6-7; Mark 2:7). The Bible ascribes these characteristics to God alone.
THE SON, JESUS CHRIST, IS GOD
The Bible ascribes the same attributes of God to His Son, Jesus Christ (Matthew 1:21-23; 28:18; Luke 5:20-24; John 1:1,14; 8:58; 16:30, 17:5; Hebrews 13:8). Jesus Christ is worshiped (Matthew 14:31-33; 28:8; Hebrews 1:6); He is called God (Isaiah 9:6; Matthew 1:21-23; John 1:1,14; 20:28), and He can forgive sins (Luke 5:20-24; John 10:30-33). These attributes are ascribed to God alone.
THE HOLY SPIRIT IS GOD
The activities and characteristics of God are attributed to the Holy Spirit (Psalm 139:7-10; Luke 1:35; 11:13; John 14:26; Hebrews 9:14). The Holy Spirit is a person (John 16:13-15; Romans 8:27; 1 Corinthians 2:10-13; 12:11), He is Creator (Genesis 1:2; Job 33:4), and He is called God (Acts 5:1-11).
A RATIONAL, BIBLICAL CONCLUSION
For the above reasons and more, we are left with no other rational, biblical conclusion than to believe that God the Father, God the Son (Jesus Christ), and God the Holy Spirit exist as a Holy Trinity: the one God of the Bible. There is no question of the existence of the Trinity, the only question is one of belief. We should want to know God, not as we think He should be, but simply as the Bible reveals Him to be.