Originally Posted by py3ak

I think the argument would go that we are commanded to sing Psalms, hymns, and spiritual songs, and hymn-singers are unconvinced that this is a reference to the titles of the Psalms (which is a discussion all by itself). From those same texts (Ephesians 5:19 and Colossians 3:16) it is plain to see that singing is a form of teaching, and of course since many of the Psalms are prayers it seems that prayers may also be sung). Now the content of prayer and teaching is regulated by the Scripture; but the exact expressions are not (in the sense that we can vary the phrasing, not in the sense that we can babble unorthodoxy). So in our teaching and praying through song we have the same freedom as in our teaching and praying through words. Therefore, uninspired compositions may be used for singing in the corporate worship of God. Or so the argument would typically run.