As a step toward restoring that peace, let us grant that both of us are committed to the regulative principle, but disagree in its application. The regulative principle does not require that every particular thing done in connection with worship be warranted by Scripture (e.g., "circumstances" such as sitting in a pew, starting at 11:00 A.M., wearing a tie), but that every "element" of worship as such -- everything invested with liturgical significance (e.g. Romanist elevation of the communion tray) -- requires Scriptural justification. Is singing a separate "element" of worship or a "circumstance" of worship? If the latter, it does not require Biblical warrant according to the regulative principle. I have argued that singing is simply one means to (one circumstance through which to) pray, praise, exhort or teach -- rather than an element of worship itself. I proved this from Colossians 3:16, where singing is a form of instruction. Advocate 2 missed the point by replying (dubiously) that instruction is "only incidental" because praise is the "essential characteristic" of singing. But my argument remains. Praise may be given to God in plain voice (during prayer, preaching or testimony) as well as in song. Why would it be acceptable to praise God in a sermon with words outside of Scripture, but unacceptable to do so when melody is added to those very same words and the congregation sings them?
To this Advocate 2 has no answer whatsoever -- beyond calling it "sophistry" and alleging it to have a "sinister practical effect." Until he refutes the claim, we should conclude that singing uninspired hymns no more violates the regulative principle than does preaching or praising or exhorting with uninspired words.
Now let me address a few incidental points in Advocate 2's reply. (1) Is it really "Dispensationalism" to argue that New Covenant worshippers have a fuller revelation and better administration of the covenant of grace than Old Covenant worshippers? See the Westminster Confession of Faith VII.5-6. It was not penned by dispensationalists. New Covenant worship should reflect the progress of redemptive history and revelation.
(2) Does Scripture warrant the singing of uninspired hymns in New Covenant worship? Advocate 2 says "no," claiming "Scripture nowhere warrants humanly composed songs in public worship." But I believe Colossians 3:16 and Ephesians 5:19 give that very warrant -- referring to "psalms, hymns and spiritual songs" (not "psalms, psalms and psalms"). Advocate 2 attempts to dismiss this Biblical evidence by claiming that it "may only" pertain to informal conduct of Christians," rather than to public worship. It would be natural to suppose that when Paul speaks of believers singing with grace in their hearts and admonishing one another with hymns, he is referring to believers gathered together and engaged in worship. (How often do we sing to each other as part of informal hospitality?) On what basis does Advocate 2 say otherwise and restrict Paul's referent to activity outside of congregational worship? Arbitrariness is not a convenience the theologian may indulge.
(3) Advocate 2's response continues certain exegetical mistakes. The words of praise in Ezra 3:11 are not identical (no more, no less) with Psalm 106:1. Even Advocate 2 admits that II Samuel 22 is not identical with Psalm 18, noting the verbal alterations. The "natural" meaning of I Corinthians 14:26 is not that an Old Testament psalm has been charismatically selected; this is not natur- al, but stems from a theological preconception. The content of the "psalm" is given by the Spirit, just as in the case of the "teaching, revelation, or tongue" which are mentioned right along side of it. Finally, regarding Colossians 3:16 and Ephesians 5:19, Advocate 2 concedes that "spiritual" song need not, given Scriptural usage elsewhere, denote the special work of the Holy Spirit (inspiration) -- in which case his conclusion about singing in worship rests upon an insufficiently supported personal preference (an unwitting departure from the regulative principle).