Just Psalms? How about Ephesians and Colossians?

From time to time, people ask me about why Christians might sing only Psalms in the worship of God. One of the more understandable arguments they sometimes present is an appeal to one or both of these verses:

Ephesians 5:19 Speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord;
Colossians 3:16 Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord.

My response to them on this is that we need to look at how the terms Paul uses would have been understood to people in a 1st century context. In that context, there was no "Trinity Hymnal" nor any "Praise Song" transparencies or the like. So, Paul wasn't speaking about three different sources, i.e. the Psalter, the Hymnal, and the Praise Songs licensed by CCLI.

What was Paul referring to? He was referring to the Psalter. This may seem surprising, because we have so closely associated the term "Psalm" with the book of Psalms, whereas we have associated the word "Hymn" with songs that aren't in the Psalter.

Nevertheless, the terms translated "psalms," "hymns," and "songs" are three of the four words commonly used in the Septuagint titles of the Psalms. Specifically: ψαλμοσ (Psalm)(66 times), συνεσεοσ/συνοισ (understanding or wisdom)(13 times), υμνοισ (hymn)(6 times), and ωδη/ωδησ (song or ode)(36 times). (see more detailed analysis here)