You won't find the word or a clear definition of the Trinity anywhere in Scripture. The term "Trinity" was developed, as are many other theological terms, in order to summarize a biblical concept. In other words, theologians did not create the concept of the Trinity, rather, they merely recognized what God has revealed about his tri-personality in Scripture. It would be impossible for us to know that God is triune without the Bible because it is a fact exclusively revealed in Scripture. No amount of philosophical speculation and reasoning could lead us to conclude that God is one in three persons. But when we take our time to adequately search the Scriptures, we can see that it progressively reveals, from Genesis to Revelation, that God is indeed triune.
What does it mean that God is triune?
The Trinity is defined as one God eternally existing as three equal yet distinct persons, Father, Son, and Spirit.
United in Essence (Divine Being/Attributes):
When we talk about the attributes of God, we have a proclivity to think that we are only speaking of the Father’s qualities, opposed to the Son and Spirit. This inevitably leads to making them both inferior to the Father. So it is essential that we do not distinguish between God’s tri-unty in terms of their essence, rather, by each persons activity and relationship to one another. As we study the Scriptures, we can see three persons that are recognized as God.
1. The Father is Fully God: 1 Peter 1:2 says , “2 according to the foreknowledge of God the Father, in the sanctification of the Spirit, for obedience to Jesus Christ and for sprinkling with his blood…”
2. The Son is Fully God: Titus 2:13 says, “13 waiting for our blessed hope, the appearing of the glory of our great God and Savior Jesus Christ,”
3. The Spirit is Fully God: Acts 5:3-4 says, “3 But Peter said, “Ananias, why has Satan filled your heart to lie to the Holy Spirit and to keep back for yourself part of the proceeds of the land? 4 While it remained unsold, did it not remain your own? And after it was sold, was it not at your disposal? Why is it that you have contrived this deed in your heart? You have not lied to man but to God.” Here we see that Peter makes no distinction between lying to the Holy Spirit and lying to God, because the Holy Spirit is God.
Each person is not just a part of God, rather, the three persons possess Divine attributes in equal measure. This means that the Father is no more powerful than the Son, and the Son is no more powerful than the Spirit and so on.
Distinct in Roles (Creation/Salvation):
But this does not mean that the Father, Son, and Spirit are the same person. The Father is not the Son or the Spirit, the Son is not the Father or the Spirit, and the Spirit is not the Father or the Son. The facts of Scripture unequivocally compel us to conclude that these are three equal yet distinct persons. So in what way does Scripture distinguish one from the other? We can begin by making the following observations (points one and two taken from Bancroft’s Christian Theology and point three from Grudem's Systematic Theology):
1. The Father is Distinct from the Son: Christ distinguishes the Father from himself as “another” (John 5:32, 7). The Father and Son are distinguished as the sender and sent, and the begetter and the begotten (John 10:36; Gal. 4:4; Ps. 2:7; John 1:14; 3:16).
2. The Father and the Son are persons distinct from the Holy Spirit: Jesus distinguished himself from the Father and Spirit (John 14:16-17), the Spirit is distinguished from the Father (John 15:26), and the Spirit is sent by the Father and the Son (John 14:26; 15:26; Gal. 4:6).
3. We can see their distinction by their roles in creation: In Genesis 1, we see that God the Father brought creation into existence by the word of his power and that the Spirit was sustaining and manifesting God’s presence in his creation by, “hovering over the waters”. In the New Testament we see that Jesus was the divine agent through whom creation was made (John 1:3; 1 Cor. 8:6; Col. 1:16; Heb. 1:2).
4. Ultimately, God’s triune nature is best understood by each persons specific role in redemption: The New Testament reveals that we are saved by a triune God. The Father plans salvation (John 3:16; Gal. 4:4; Eph. 1:9-10), the Son accomplishes salvation (John 6:38; Heb. 10:5-7, etc), and the Spirit applies salvation (John 3:5-8; Rom. 8:13; 2 Thess. 2:13; 1 Peter 1:2).
United in Purpose (Glory of God/Joy of Man):
As stated above, God is revealed as three persons, Father, Son, and Spirit, who are equally God yet distinct in activity. Although they have unique roles, they are not at odds with one another. They are wholly committed to loving, serving, and glorifying one another. The Father did not begrudgingly raise Christ from the dead, just as the Son did not begrudgingly obey the Father. In creation and salvation, each person is deeply committed to their unique role and unified purpose. John Frame says, "The Father, Son, and Spirit stand together as Creator and Savior, and are therefore equally deserving of praise and thanksgiving." Our worship should be saturated with praise for each Divine persons role in our creation and salvation.
Implications of the Doctrine of the Trinity
For the sake of brevity, I will only focus on a few implications that we can draw from God's triune nature.
1. God is love: John Frame says that, "Christians frequently speak of God’s love being defined by his relationship between himself and the world. But if this were the case, then one of God’s essential attributes would be dependent upon there being a world: God would have needed the world in order to have an object for his love." God didn't need creation in order to exercise his divinity. The theological term for this is independence, meaning God's essence is not dependent on anything outside of himself. The doctrine of the Trinity shows us that love has eternally existed between Father and Son, and therefore God would still be loving if he chose not to create the world. The application of this is that God did not create us because he needed to love something, but because he freely chose to love us out of his abundance.
2. God is personal: God has been eternally existing as a community of Father, Son, and Spirit. Wayne Grudem says that, "The interpersonal relationships between the three persons show us that God is genuinely personal." Before the foundations of the earth, perfect unity and love existed between each person of the Trinity. So He did not need creation in order to be personal. Now, we can understand that we are personal creatures by virtue of imago Dei (being made in the image of God). The application of this is that we were not built for isolation, rather, we were designed to be in community, mirroring the self-giving love of the Father, Son, and Spirit.
3. God is glorious: These two points reveal the glory of God. Because God has been eternally independent and satisfied in himself, he needs absolutely nothing. Jeremy Treat of Reality LA says, "God’s glory is wrapped up in his giving...he is glorified in giving love that satisfies the other." On the cross, we see God’s self-giving love put on display for all of humanity. We love, give, and serve others because it is a reflection God's character.
We are saved by, and have communion with, the triune God of the universe. My prayer is that we would experience the joy of Trinitarian life: may we pray to the Father, through the Son, and by the power of the Spirit; that we will grow in the image of Christ, by the power of the Spirit, and to the glory of the Father. Amen.