The Trinity, that word we use to describe the oneness of God and that He is a community within Himself. This is one of those theological concepts that is easier to affirm than it is to understand. But the reality is that a perfect, loving, inexhaustible God made Himself known to a flawed, limited, vulnerable people. How God did this is a mystery that can’t be fully understood.
It was a mystery that God would send his Son to be born to a young virgin named Mary (Luke 1:26-45). It was a mystery that a host of angels would proclaim His coming to humble shepherds (Luke 2:8-20). And it was a mystery that a little Jewish Boy, born in a manger, would redeem the entire world. We can’t understand it, we can’t explain it, but God’s revelation attests to it: God desires to make Himself known to us, His creatures. He makes himself known through his creation. He makes himself known through His word, both spoken by the prophets and recorded in our scriptures. And He makes Himself known as Father, Son, and Holy Spirit.
When God delivered the people of Israel out of slavery in Egypt, He revealed Himself to be the one and only God worthy of their affection and their worship. This is the truth we find in the Shema, or Deuteronomy 6:4-5. These two verses make up the heart of the Jewish confession of faith. There is one God, with one Spirit. And God and His Spirit have been present in creation from the very beginning of time (Genesis 1:1).
This is what Jesus was taught and what Jesus believed. It is also the core of “the faith that was once for all delivered to the saints” (Jude 1:3), what every believer has been taught and has confessed from the beginning of the church on the day of Pentecost (Acts 2).
But beginning even before the birth of the church, those who believed in Jesus did so because they recognized Him as God in the flesh (John 1:1-5). They’d witnessed “the Spirit of God descending like a dove and coming to rest on him” (Matthew 3:16), and they’d heard a voice from heaven say, “This is my beloved Son, with whom I am well pleased” at His baptism (Matthew 3:17).
God reveals Himself in three persons: Father, Son, and Holy Spirit. Any other god is not the God of the Scriptures. Any other god is but a cheap imitation, an illusion, an idol. Because we believe in the God who reveals Himself, we add our voices to the voices of the church, our brothers and sisters across time and space and culture, and confess,
We believe in one God, the Father Almighty, maker of heaven and earth and of all things visible and invisible. And in one Lord Jesus Christ, the only begotten Son of God, begotten of his Father before all worlds, Light of Light, very God of very God, begotten not made, being of one substance with the Father, by whom all things were made… And [we believe] in the Holy Ghost, the Lord and Giver of life, who proceeds from the Father, who with the Father and the Son together is worshipped and glorified, who spoke by the prophets.1