The Doctrine of the Trinity
The word "trinity" never appears in the Bible, but there are both obvious and subtle clues that lead to the Doctrine of Trinity. In Deuteronomy 6:5, the Bible tells us that "The Lord is One." Monotheism, or the belief in one god, was a bold statement to make in biblical times when many gods were worshipped. It set Christianity apart from the other religions.
Some subtle clues can be found in Genesis 1:26, "Let us make man in our image." Genesis 1:1 "In the beginning there was God." In the original Hebrew translation, the word used for God is Elohim. Elohim is a plural noun. In verse 2, the Spirit of God is hovering above the waters. The phrase "And God Said" is used repeatedly in Genesis to explain that God's Word brings about creation. In John 1:1, we are told that "In the beginning was the Word, and the Word was with God, and the Word was God." In John 1:14, we learn that "the Word became flesh" which we now know was Jesus Christ.
When Jesus was baptized, the voice of God spoke and the Spirit of God decended like a dove upon Jesus. All three persons of the trinity are in attendance for all to see. In the Great Commission, all three persons are mentioned when we are told to baptize believers in the name of the Father, Son and Holy Spirit. At the end of Paul's letters, he writes: "May the grace of the Lord Jesus Christ and the love of God, and the fellowship of the Holy Spirit (2 Corinthians). One God, three persons... God the Father, God the Son and God the Holy Spirit.