“Classical Protestant theologians spoke of two foundations of the church’s doctrine and life. They identified Holy Scripture as the cognitive foundation, the supreme source and norm of all the church is called to believe and to practice, the foundation of ‘the truth, which accords with godliness’ (Titus 1:1).
In addition to this cognitive foundation, they identified the triune God as the ontological foundation of the church’s doctrine and life. As all things are ‘from’ and ‘through’ and ‘to’ the triune God in the order of being (Rom. 11:36), so, they judged, all things are from and through and to the triune God in the order of theological understanding and Christian living.
The doctrines of creation and providence, the person and work of Jesus Christ, the church and sacraments, salvation and last things– each of these doctrines rests on the doctrine of the triune God for its meaning and significance, and the life of godliness that builds on these doctrines directs us to the triune God as our supreme good and final end.
The confession that Jesus is the Christ, the Father’s Spirit-anointed Son, is the foundation of the Christian confession (Matt. 16:16; 28:19; Mark 12:1-12; Eph. 2:20).
For this reason, the doctrine of the Trinity is the foundation of Christian teaching and living. Without the doctrine of the Trinity, there is no Christianity.
One of the major missteps recent trinitarian theology took was to suggest that the Trinity is only meaningful insofar as we can demonstrate its usefulness for various practical, social, and political ends.
But this is to get things utterly backwards.
The Trinity does not exist for our sake or for the sake of our agendas.
The triune God is not a means to an end. We exist for Him (1 Cor. 8:6).
The Trinity is an end in Himself (Rom. 11:36).
Therefore, studying the Trinity– seeking better to know and understand, to cherish and adore, to worship and serve the triune God– needs no justification beyond itself.
The reason for studying the triune God is not to bend the Trinity to our various social programs.
The reason for studying the triune God is to bend our minds, wills, actions, and communities to the Trinity, confident that, in doing so, we will discover in Him both the reason for our existence and the fullness of joy (Ps. 16:11; John 15:11; 17:13).”
–Scott R. Swain, “Foreword,” in Matthew Barrett, Simply Trinity: The Unmanipulated Father, Son, and Spirit (Grand Rapids, MI: Baker, 2021), 13-14, 15-16.