2 Corinthians 13:14 (ESV) … “The grace of the Lord Jesus Christ and the love of God and the fellowship of the Holy Spirit be with you all.”
Paul’s final blessing on the Corinthians invokes all three members of the Trinity—the Father (God), the Son (Lord Jesus Christ), and the Holy Spirit. Although the term “Trinity” is not explicitly used in the Bible, verses such as this one show that early Christians believed that there were three persons in the Godhead: God the Father, Jesus the Son, and the Holy Spirit (for more verses on the Trinity, see Matthew 3:17; 28:19; Luke 1:35). Denying that Jesus is God would mean denying that his death on the cross could provide God’s unmerited grace to those who believe in Jesus. Denying that the Holy Spirit is God would mean denying that the Spirit could provide believers fellowship with God and each other.
With this final Trinitarian benediction, Paul was giving the Corinthians a model from the Godhead of how to be unified in love. Through the Spirit’s empowering, they, too, could begin to imitate in their congregation the grace, love, and fellowship that the Godhead already enjoyed.
Paul had every right to refuse to communicate with the Corinthians until they reformed their ways. Instead, Paul loved them and mercifully reached out to them with visits and letters, again and again. This type of persistent love was the type of grace Jesus had shown Paul. Although Paul had persecuted the church (1 Timothy 1:13), Jesus had graciously shown him mercy. In the same way, Paul didn’t withdraw himself from the Corinthians when they began to reject him. He didn’t exclude them from fellowship. Instead, he expressed love and concern for them. He prayed for them. He even lovingly warned them about the false teaching and the immorality in the congregation. It was by his commitment to the Corinthians—through good times and bad, through rejection and acceptance—that Paul hoped to bring the Corinthians back into the full enjoyment of Christ and Christian unity.
Paul prayed for grace, love, and fellowship with the persons of the Trinity because these blessings are so essential to the spiritual well-being of the church. Divine grace is the unmerited mercy of God toward his people, granting them forgiveness of sin. Divine love is God’s affection and loyalty toward his true people that secures them in a saving relationship with him. Divine fellowship is the experience of the nearness of God that encourages and empowers believers in their daily walk before him.
Paul wanted all this and more for the congregation at Corinth. Despite the troubles they had given him over the years, his desire was to see them enjoy the rich blessings of God in their lives. If they would take his epistle to heart, they would surely receive those blessings.
 Barton, B. B., & Osborne, G. R. (1999). 1 & 2 Corinthians (pp. 473–474). Wheaton, IL: Tyndale House.  Pratt, R. L., Jr. (2000). I & II Corinthians (Vol. 7, p. 443). Nashville, TN: Broadman & Holman Publishers.