He writes in his book To What End Exegesis?: Essays Textual, Exegetical, and Theological (Eerdmans 2001), 333, 334:
At the heart of Paul’s theology is his gospel, and his gospel is essentially about salvation – God’s saving a people for his name through the redeeming work of Christ and the appropriating work of the Spirit. Paul’s encounter with God in salvation, as Father, Son, and Holy Spirit, alone accounts for the expansion and transformation of his theological language of God and of God’s saving work. In light of this reality and the great number of texts that support it – with trinitarian language – these passages rightly serve as the starting point for any study of the Trinity in Paul.
The remarkable grace-benediction of 2 Cor. 13:14 offers us all kinds of theological keys to Paul’s understanding of salvation, and of God himself. The fact that the benediction is composed and intended for the occasion, rather than as a broadly applicable formula, only increases its importance in hearing Paul. This what he says here in prayer appears in a thoroughly presuppositional way – no at something Paul argues for, but as the assumed, experienced reality of Christian life.
First, it summarizes the core elements of Paul’s unique passion: the gospel, with its focus on salvation in Christ, equally available by faith to Gentile and hew. That the love of God is the foundation of Paul’s view of salvation is stated with passion and clarity in passages such as Rom. 5:1-11; 831-39; and Eph 1:3-14. The grace of our Lord Jesus Christ is what gave concrete expression to that love; through Christ’s suffering and death on behalf of his loved ones, God accomplished salvation for them at one moment in human history.
The participation in the Holy Spirit continually actualizes that love and grace in the life of the believer and the believing community. The koinonia, (“fellowship/participation in”) of the Holy Spirit is how the living God not only brings people into an intimate an abiding relationship with himself, as the God of all grace but also causes them to participate in all the benefits of that grace and salvation – that is, by indwelling them in the present with his own presence, and guaranteeing their final eschatological glory.
Second, this text also serves as our entrée into Paul’s understanding of God himself, which had been so radically affected by the twin realities of the death and resurrection of Christ and the gift of the Spirit. Granted, Paul does not here assert the deity of Christ and the Spirit. What he does is to equate the activity of the three divine persons (to use the language of a later time) in concert and in prayer, with the clause about God the Father standing in second place(!). This suggests that Paul was in fact trinitarian in any meaningful sense of that term – that the believer knows and experiences the one God as Father, Son, and Spirit, and that when dealing with Christ and the Spirit one is dealing with God every bit as much as when one is dealing with the Father.
Thus, this benediction, while making a fundamental distinction between God, Christ, and Spirit, also expresses in shorthand form what is found everywhere throughout his letters, namely, that “salvation in Christ” is the co-operative work of God, Christ, and the Spirit.
Get it? Got it? Good! 🙂