"15 Look carefully then how you walk, not as unwise but as wise, 16 making the best use of the time, because the days are evil. 17 Therefore do not be foolish, but understand what the will of the Lord is. 18 And do not get drunk with wine, for that is debauchery, but be filled with the Spirit, 19 addressing one another in psalms and hymns and spiritual songs, singing and making melody to the Lord with your heart, 20 giving thanks always and for everything to God the Father in the name of our Lord Jesus Christ, 21 submitting to one another out of reverence for Christ."
Ephesians 5:15-21
The third term, 'spiritual songs', is different again. They are not 'psalms', in that they are distinct from the Psalter itself; they are not 'hymns', since they do not direct an address of praise to God; but they are authentic expressions of spiritual aspiration, covering the whole range of spiritual experience, Christian thought and feeling. In this, they share a common ground with many of the Psalms, which of course express wonderful depths of joy and sorrow, distress or exaltation (in this sense, although 'spiritual songs' are not 'psalms', many psalms partake of the essential characteristics of spiritual songs). How, then, could it be unsuitable to sing them in public worship? To relegate utterances such as Psalm 40, or Psalm 55, or Psalm 130, to name but a few, from public worship would surely be unthinkable, and just as unthinkable to exclude some of the great 'spiritual songs' that have blessed the people of God down the ages.
The real point at issue is not that 'spiritual songs', with their subjective emphasis should be discounted, or excluded from public worship, but that undue sentimentalising of spiritual experience should be avoided, and excessive preoccupation with subjective feelings. It is possible to be too engrossed in one's spiritual health, and become a spiritual hypochondriac; possible, too, in a service of worship to be so taken up with one's cares and burdens that God Himself is displaced from our consciousness. And this is where the robust, outward-looking emphasis of the great hymns of the Faith, that magnify the name of God and of Christ, provide such a salutary safeguard and counteractive, lifting the heart from its woes to the All-sufficient God Who can supply all our needs. It is all a matter of balance; but in true Christian worship, singing and making melody in our hearts to the Lord, there can be little doubt as to where the primary emphasis should lie.