1. Philip Cary

We could say: in Christ, God has entered the drama of human history. But it might be more accurate to say that through Christ human history is caught up in the drama between Father, Son, and Holy Spirit unfolding in the Gospel. For to receive Christ in faith is to participate in his story and share his life. By faith alone we abide in Christ as he abides in us, so that our life is hidden with Christ in God, and when he appears we shall appear with him and be like him. Being incorporated into Christ’s body, we are brought into the drama that is the eternal life of the Trinity.

from The Meaning of Protestant Theology (Baker, 2019), 310.

2. Donald Fairbairn

We can understand and appreciate the various aspects of Christian teaching and Christian life in relation to the fundamental relationship between the Father and the Son. God created us to share in this relationship and gave us a share in the communion of the Trinity at creation. This is the primary thing that we lost through the Fall. God’s promise after the Fall, around which one may organize the entire history and teaching of the Old Testament, was ultimately a promise that the Son of God would come to bring human beings back into a share in the communion of the Trinity. In fulfillment of this promise, God the Son personally entered human life by becoming man while remaining God, and in his human life he showed us both God’s love and perfect human love. At his crucifixion, God the Son bore in his own person our estrangement from God; as man he was crushed by our sin, and as man he was forsaken in our place by his own Father. Through his resurrection and ascension, he was restored as man to the fellowship of the Trinity which he had always shared as God, and in the process he opened the way for people who are united to him by faith to be restored to fellowship with the Trinity as well. The Holy Spirit, whom the Father and the Son sent to earth, dwells in believers, uniting us to the Son and thus granting us the participation in the Father-Son relationship that became possible through Christ’s life, death and resurrection. Through the Spirit, Christians are called to live—both individually and as the church—so as to anticipate the time when God will transform the entire created world and bring his dwelling here to be with his people for eternity.

from Life in the Trinity (IVP Academic, 2010), 232-233.

[one of the better single-paragraph summaries of Christian faith I’ve come across in a while]