Relating this biblical text to the liturgical context is no easy thing. Because the setting is Trinity Sunday, many preachers will feel pressure to call on these verses to prove or explain the doctrine of the Trinity. The results, almost certainly, will not be pretty.
This reading is the lectionary's attempt to summon a passage into service to provide the theological resources for illustrating or legitimizing an occasion in the liturgical calendar. Many preachers will focus sermons solely on this text so as to use the final verse of 2 Corinthians to launch a doctrinal sermon on Trinitarian theology. I beg you not to do that. One reason why: how many people hear sermons that try to explain the Trinity and then return home exclaiming, "Wow! That really helped!"? My other reason has to do with the need to listen to the biblical text and, in doing so, to understand a sermon's purpose in leading people into an encounter with God as opposed to a treatise about God.
Considering the text, its message is not Trinitarian, strictly speaking, at least not in a "capital-T" sense of the word. That is, it does not adequately express the affirmations and nuances of the classical Trinitarian doctrine that was formulated in the centuries after Paul lived. Notice that 2 Corinthians 13:13 (which appears as 13:14 in some versions, such as the TNIV and RSV) explicitly names just two Persons of the Godhead, Jesus Christ and the Holy Spirit. A strictly Trinitarian expression would not assume that "the love of God" was fully equivalent to "the love of the Father." Also, Paul's ordering differs from the traditional Trinitarian sequence of Father, Son, and Spirit. All this is to acknowledge that Paul--as demonstrated not only here but also in the rest of his letters--was not himself "Trinitarian," as Christian doctrine came to understand the term and its implications. His aim was hardly to define God and God's nature in precise, abstract categories.
Another problem with letting Trinitarian concerns determine our reading of this passage is that doing so easily obscures the purpose that Paul's language about God serves in 2 Corinthians 13. The focus is relatively simple: God is the source of grace, love, and community.
It was crucial that the Corinthians were made aware--just as it remains crucial for us to be made aware--that God provides all that heals and benefits God's people. The final four chapters of 2 Corinthians constitute a tense and combative communication to a church that had begun to oppose Paul and question the validity of his message. The testy apostle concludes his remarks with a series of rapid-fire appeals and encouragements in 13:11. The grammar is ambiguous, leaving it not entirely clear which utterances make appeals and which offer encouragements. The word for "farewell" could also be rendered as "rejoice." "Put things in order" could be "be restored to order." "Listen to my appeal" is better understood as "encourage one another." Whatever the precise meaning, clearly in these and the other words of 13:11 Paul points toward the possibility of reconciliation--both between himself and his readers, and among the Corinthians themselves. It is no small thing that the verse ends with a promise about "the God of love and peace," followed by a command to enact love and respect through "a holy kiss" and finally a benediction concerning the grace, love, and communion that God gives. In multiple ways, God makes it possible for the family of faith to affect and embody reconciliation and peace.
And so, even though this passage does not define God as One who lives and operates in relationship among three Persons, it nevertheless makes important statements about what God provides and how God provides it. Paul describes God as deeply engaged with people through the gospel of Jesus Christ.
It will now be helpful to revisit my earlier insistence that these verses are not Trinitarian. It should be clear that I am not saying that this passage has no relevance for Trinity Sunday. Certainly Paul's words here were among those that adumbrated and later provoked the theological conversations that would eventually formulate Trinitarian doctrine. In this regard, one could claim that the tripartite structure of 2 Corinthians 13:13 ascribes a faintly trinitarian ("small-t") character to Paul's proclamation of the gospel. That is, the verse recognizes essential overlap and connection among various ways in which God reaches out to people. Precisely this aspect of the text--the idea of God being in contact with humanity--makes the passage most interesting for consideration on Trinity Sunday. The doctrine of the Trinity makes no sense and serves no purpose if we treat it as abstract dogma. It becomes necessary and helpful only because it stems from believers' first acknowledging that God has acted in various ways--especially through Jesus Christ and through the presence of God's indwelling Spirit. When Paul roots grace in the Lord Jesus Christ, he (following other Christians of his time) clearly has made a foundational move of discovering and naming the reality of God's work through Christ. In coming to name Christ as Lord and finding grace there, Paul has taken the first steps--minor yet bold first steps--toward understanding that God's love extends to humanity in multifaceted ways.
Even if those who preach on this text should not expect to find in it a clear statement of God's Trinitarian nature, they can lead people to explore more deeply some of the language that is at the heart of Christian belief and worship. Many congregations will be very familiar with the words of 2 Corinthians 13:13 from the greetings and benedictions they regularly hear on Sundays. This gives preachers opportunities to reflect with congregations on exactly what they mean when they pronounce this benediction before others. At the very least, it means that we acknowledge God's commitment to us and our accountability to God to be instruments of grace, love, and community among one another and within the wider world.