The Trinity is one of the great theological mysteries. There are some who think that because we believe in monotheism, one God, we cannot accept the concept of the Trinity. Yet the Bible teaches that the Godhead consists of three divine Persons--Father, Son, and Holy Spirit--each fully God, each showing fully the divine nature (see Matthew 3:16-17).
The Father is the fountainhead of the Trinity, the Creator, the first cause. He is the primary thought, the concept of all that has been and will be created. Jesus said, "My Father has been working until now, and I have been working" (John 5:17).
The Son is the "Logos" or expression of God--the "only begotten" of the Father. If you want to know what the Father is like, look at the Son. In John 14:9, Jesus said, "He that has seen me has seen the Father." The Son of God is the agent of creation and our redeemer.
The Holy Spirit, the third Person of the Trinity, proceeds from the Father and is worshiped and glorified together with the Father and the Son.
The Father, as prime mover, brings forth the creative thought. The Son, as agent of creation, expresses that thought. The Spirit activates the creative word and relates it to that which is created. He inspired the Scriptures and empowers God's people. He takes the things of Jesus and brings them to our remembrance. John 16:8 tells us that He convicts the world "of sin, and of righteousness, and of judgment."
All three Persons of the Godhead are eternal. The Father exists and has existed forever. With Him always existed His expression, the Son. Always the Father loved the Son, and the Son loved and served the Father. From that relationship of love arose the Spirit of God, who is eternal and has existed forever. There was, therefore, not a time when there was only the Father, then later the Son, and still later the Spirit. They all three have existed from before there was anything that could begin--three distinct Persons all functioning as One.
There are trinities in nature. Light can be divided into three primary colors; yet light is one. A prism will reveal the individual colors separately that are unique yet unified. An example of a trinity in nature which is sometimes given erroneously to explain the Trinity is the transformation of water to steam or to ice. The problem with this illustration is that water becomes either steam or ice, but does not at the same time remain water. This type of thinking leads to a heresy called modalistic monarchianism, which maintains that the Father changes into the Son or into the Spirit--different modes of the same being but never the three beings at one time.
Upon the occasion of Jesus' baptism, however, all three persons in the Trinity were present and active. The Father spoke from heaven, the Son was fulfilling all righteousness, and the Spirit descended upon the Son like a dove (see Matthew 3:16-17, Mark 1:9-11, Luke 3:21-22).
The existence of the Trinity is a mystery that one day we will understand clearly. For now, we know that the Bible teaches it and Jesus revealed it, and the Christian church from the beginning has confessed and safeguarded this precious truth.