I 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.
I Corinthians 14:26:
How is it then, brethren? when ye come together, every one of you hath a psalm, hath a doctrine, hath a tongue, hath a revelation, hath an interpretation. Let all things be done unto edifying.
Some argue that these passages support the use of hymns in worship because Paul seems to be speaking of singing extemporaneously. However, this need not be the interpretation of this passage.
First, Paul’s use of the term psalm in verse 26 should be interpreted in the context of all the other New Testament writings on the subject. The term psalm is exclusively used to refer to the singing of the Old Testament psalms. The singing mentioned in verse 14 was then the singing of psalms, based upon the context of verse 26, where psalms are mentioned.
Second, I Corinthians 14:15 does not necessarily have to mean singing extemporaneously, as so many argue.
Roy Ciampa and Brian Rosney argue in their commentary on 1 Corinthians that we do not have to assume these are new compositions (although they incorrectly translate the word psalmos as hymn and do not deny that it could be something new). They state, “A hymn [psalm] could be a known composition or something fresh, but there is no reason to assume it was spontaneous.”
Anthony Thiselton holds the position that we cannot know either way. He writes, “The text simply does not specify whether a worshiper brings a choice of psalm or has (has composed or is in the process of composing) a hymn.”
CF. W. Grosheide seems to favour that this is referring to psalm singing, though he does not rule out hymnody. He writes, “One possesses the charisma of uttering a psalm in a special manner (he may even have composed a psalm or have sung a Christian hymn.”
Christian Wolff more strongly argues in Der erste Brief that “the choices of psalm and teaching are ‘not spontaneous.'”
While it may not be known either way based upon simply a reading of I Corinthians, I argue it can be determined based upon a reading of the whole NT (e.g. Ephesians 5:19 and Colossians 3:16) and the consistent practice of psalm singing in the NT church. Calvin argues that Paul here refers to Psalm singing:
“When he says, I will sing Psalms, or, I will sing, he makes use of a particular instance, instead of a general statement. For, as the praises of God were the subject-matter of the Psalms, he means by the singing of Psalms—blessing God, or rendering thanks to him, for in our supplications, we either ask something from God, or we acknowledge some blessing that has been conferred upon us. From this passage, however, we at the same time infer, that the custom of singing was, even at that time, in use among believers, as appears, also, from Pliny, who, writing at least forty years, or thereabouts, after the death of Paul, mentions, that the Christians were accustomed to sing Psalms to Christ before day-break. I have also no doubt, that, from the very first, they followed the custom of the Jewish Church in singing Psalms.”
So the argument that you must accept hymnody based upon I Corinthians 14 simply does not hold true. As the commentators quoted in this post have shown, one does not have to assume that Paul is speaking of extemporaneous singing and composing. It can, just like a teaching, be prepared and not spontaneous. Further, the use of the word psalm in verse 26 qualifies the singing in verse 15, giving added weight to the argument that these were prepared psalms from the OT that they were singing.