Paul upholds the deity of the Holy Spirit when he states, "The Lord is the Spirit" (2 Cor. 3:17; cf. v. 18). Although some identify kyrios as the God of the Old Testament, it seems preferable, given the immediate context (v. 14), to hold that the apostle identifies Christ and the Spirit. That being so, "The Lord and the Spirit are ‘one’ in the same sense that Jesus said that He and the Father were one (John 10:30).
Bruce Demarest and Gordon Lewis, Integrative Theology, vol. 1 (Grand Rapids, MI: Zondervan, 1987), p. 266; the last sentence quotes R. V. G. Tasker, 2 Corinthians, Tyndale New Testament Commentaries (Grand Rapids, MI: Eerdmans, 1983), p. 66