Where does the Trinity Doctrine come from? I can not find the word "Trinity" in the Holy Bible. When and how did it originate?
Although the word 'Trinity' is not mentioned in the Bible, many verses prove the doctrine of Trinity. Our Lord Jesus Christ in His great commission to the disciples told them "Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit" (Mt 28:19). So since the apostolic time believers were baptizing in the name of the Father, Son and Holy Spirit.
In the second century A.D. Tertullian (150 - 225 AD) became the first man to use the word "Trinity" in association with the Godhead. He also was the first to say that God was Three persons in one substance about the year 200.
Origen (185 AD - 254 AD) refined the doctrine a bit more. In his book 'On the Principles' he states that our Lord Jesus Christ was born of the Father before all other creatures, and that the Holy Spirit was associated in honor and dignity with the Father and the Son. Origen was the first who clearly taught that there are three Persons, who are eternal.
In the early fourth century, a great controversy arose between those who believed that Jesus Christ was another being separate from God and inferior to God, and those who believed that Jesus Christ was a coeternal Person beside the Father making up one God. St. Athanasius led the group who believed in three Persons equal in essence and one God while Arius led the other group.
To resolve this controversy the council of Nicea was called in 325 A.D. led by St. Athanasius and stated the confession that the Son is "of the same essence as the Father'. The doctrine of the Trinity became official but was not completely finalized until the Council at Constantinople in 381 which declared God to be three eternal persons and that the Holy Spirit was the third eternal person. The Athanasian or Nicene Creed is the declaration held by all Orthodox, Roman Catholics and most Protestants today.
Some of the verses that prove the Trinity are:
"Then God said, "Let Us make man in Our image, according to Our likeness" (Gen 1:26). "Come, let Us go down and there confuse their language, that they may not understand one another's speech" (Gen 11:7).
"For unto us a Child is born, Unto us a Son is given; And the government will be upon His shoulder. And His name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace" (Isa 9:6).
"For there are three that bear witness in heaven: the Father, the Word, and the Holy Spirit; and these three are one" (1 Jn 5:7).