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. Where does this doctrine come from?
This doctrine comes from the New Testament with hints from the Old Testament. Four passages represent others.
First, at the baptism of Jesus, the Father, the Son, and the Holy Spirit were present. As soon as Jesus came up out of the water, "he saw the Spirit of God descending like a dove and lighting on him. And a voice from heaven said, This is my Son, whom I love and with him I am well pleased" (Matt. 3:16-17). The Fathers voice sounded from above and affirmed the Sonship of Jesus, and the Holy Spirit descended on him and empowered him.
Second, at the end of the same Gospel, Jesus is resurrected, and he commissions the disciples to go into all the world and preach the gospel. These two verses are part of the Great Commission, which Evangelicals take seriously. "All authority in heaven and on earth has been given to me. Therefore, go and make disciples of all nations, baptizing them in the name of the Father, the Son, and the Holy Spirit" ... (Matt 28:18-19).
This passage affirms that Jesus was granted all authority in heaven and on earth. This raises him high above a mere prophet. This passage also demonstrates Jesus early declaration of the Trinity. Therefore, this doctrine comes from him, originally.
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