In many places throughout the world, Christians observe Pentecost as a celebration of God as the Trinity — three divine persons living eternally in perfect unity: Father, Son, and Holy Spirit. The Trinity is the mystery at the heart of Christianity.
The Apostles’ monotheism was continuous with their religious heritage. God had said through the prophet Isaiah: “I am the LORD, and there is no other, besides me there is no God” (Isa. 45:5). Yet from the first day of the Church’s life, it was clear that the one God is also three. As Peter preached his first public sermon, he spoke of the Father, the Son, and the Spirit: “Being therefore exalted at the right hand of God, and having received from the Father the promise of the Holy Spirit, [Jesus] has poured out this which you see and hear” (Acts 2:33).
The God Peter preached was not a solitary being but an eternal communion. The God revealed on Pentecost was interpersonal. Only of such a deity could the Apostles say: “God is love” (1 John 4:8, 16).
The Apostles grounded this most fundamental belief in a revelation given by Jesus. In the last sentence recorded in St. Matthew’s Gospel, Jesus instructed His disciples to baptize “in the name of the Father and of the Son and of the Holy Spirit” (Mt.28:19). They were to act in one divine “name” that clearly applied to three distinct persons. Father, Son, and Spirit share the “name” of God equally. Jesus’ Great Commission, then, was the immediate back-ground for Peter’s first proclamation.
Jesus showed the Apostles something that had previously been veiled from human sight, something humanity could not have discovered on its own. The Apsotles were duty-bound to report the content of the revelation, even though they could not pretend to comprehend it.
Christians, over time, would reflect on the mystery and see hints of it in the Old Testament — in God’s use of first-person plural pronouns such as we, us, and our, for example, and in the manifestation of three heavenly visitors to Abraham.
It is clear from the preaching of the Apostles that they considered Jesus and the Holy Spirit to be divine, yet distinct from one another. Paul pronounced blessings in Jesus’ name (Rom. 16:20; 1 Cor. 16:23) and in the name of the Trinity: “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all” (2 Cor. 13:14).
This revelation arrived as something more than mere “information.” The experience of the Trinitarian God was decidedly new. The eternal Word had “pitched his tent” among His people; that’s the literal meaning of the Greek in John 1:14. And, as if that were not close enough, He promised that they would share His life in a still deeper way. He would “abide” in them, and they would abide in Him (15:4-10). They would be “filled” with the Holy Spirit (Acts 2:4; 4:8; 6:3; 6:5; 7:55; 13:52).
Editor’s note: This article is the fourth part in a 12-part series exploring the Catholic background behind NBC’s A.D. The Bible Continues (watch on Sundays at 9/8c). Check back each Friday for a new entry. As well, you can get The Catholic Viewers Guide for A.D. as well as Ministers and Martyrs, or order both as a set to save 25%.