Expositor's Bible Commentary Commentary 1 Corinthians 14:15

"What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also." — 1 Corinthians 14:15 (ASV)

Praying and singing in the spirit and mind (v.15) are involved in praising and giving thanks to God (v.16), all of which are to be a coherent part of Christian worship (Ephesians 5:18–19). “Those who do not understand” are Christians who do not understand the tongue without an interpretation, or inquirers about Christianity who do not understand the language. Such people, too, are important, Paul implies, for they also ought to be able to say “Amen” (cf. 1 Chronicles 16:36; Nehemiah 5:13; 2 Corinthians 1:20; Ephesians 3:21) to the thanksgiving conveyed in the strange language. But how can they do that and mean it, when they do not understand what they have heard? Paul grants that the tongue may in itself be conveying thanksgiving to God, but it was important for Christians without that gift to understand it (v.17).