"... speaking to one another in psalms and hymns and spiritual songs." (Eph. 5:19)
Some students of liturgics (that is, the study of the proper manner of worship) question whether responsive readings are to be used in worship. What is the biblical basis for them? What is their purpose?
Our pattern is to use responsive (or unison) readings (usually from the book of Psalms) as we prepare ourselves for the prayer of confession of sin, which follows. The biblical basis for this practice is that the Scriptures themselves tell us that the congregation should use appropriate words in its ministry to one another (Eph. 5:19; Col. 3:16). We usually think of our congregational singing in this regard, but the Scriptures command us to "speak" to one another as well as to sing to one another and to the Lord.
In the Old Testament, there is an example of this kind of congregational speaking in Deuteronomy 27. The tribes of Israel were divided between Mount Ebal and Mount Gerizim. The blessings and the curses of the covenant were read aloud, and the people responded with their "Amen!" In doing so, they committed themselves to the very things God had told them in his covenant word. We do something similar as we take God's words on our lips and recommit ourselves to them in corporate worship.
In a real sense, this time of congregational speaking is an extension of our corporate confession of faith. Because the Psalms have their ultimate fulfillment in the person and work of Christ (Luke 24:44), we are continuing our confession of him. We are also reminding one another of the multifaceted truths in a believer's experience (the Psalms are given, in part, for that purpose). Those very reminders should make us desire to come before God in repentance and confession.
What a privilege it is to take the Word of God on our own lips as we worship the God who is to be worshiped according to that Word!