The question is whether the Westminster Assembly's Confession of Faith (WCF) in Chapter 21:5 Of Religious Worship and the Sabbath Day, when it mentions the "singing of psalms with grace in the heart", is referring to the 150 psalms of the canonical variety or were the Westminster divines rather talking about psalms in the broader sense of any religious song of praise, even uninspired song. We mention this because the latest two commentaries on the Assembly's Confession by Fesko and Van Dixhoorn - as well as other presbyterians who should know better when framing the question? - conclude the latter. (As to whether one agrees with the Westminster Assembly is another question. The first thing to determine is what did the Assembly actually set forth in its documents.)
Yet there seems to be no due diligence in thoroughly examining all the primary sources. This means not only the Confession and the Catechisms, but also the Directory for Public Worship (DPW) and the Form of Presbyterial Church Government (FPCG) along with the Minutes of the Assembly and what eventually became the Scottish Psalter 1650, or the Assembly's revision of Rouse's psalter over and above Barton's.
Yet there seems to be no due diligence in thoroughly examining all the primary sources. This means not only the Confession and the Catechisms, but also the Directory for Public Worship (DPW) and the Form of Presbyterial Church Government (FPCG) along with the Minutes of the Assembly and what eventually became the Scottish Psalter 1650, or the Assembly's revision of Rouse's psalter over and above Barton's.
In other words, to suggest that "psalms" in the Westminster Standards means something other than the psalms, hymns and songs of David, Asaph and Korah in the Old Testament's Sepher Tehillim or Book of Praise, is either disingenuous or incompetent to the question. That psalmody may or may not be popular these days in or outside the P&R church is again, beside the question as to what the Westminster Assembly actually taught according to the primary sources. Likewise whatever the common use or meaning of the term "psalm" might be, whether today or in the Assembly's day is immaterial; the Assembly's use pre-empts the common usage, if not dictates how we are to understand the term, at least when it comes to the Westminster Standards, the animus imponentis of contemporary presbyterian churches notwithstanding when it comes to their affirmation of the WCF.
In other words, let there be no mistake about it. The overwhelming, if not unanimous use of the term in the Standards, along with the Minutes and the Assembly's Psalter, categorically refers to the 150 Old Testament psalms. The same, written in part by David, "the sweet psalmist of Israel" who said "The Spirit of the LORD spake by me, and his word was in my tongue. (2 Sam. 23:1,2)".
Singing of Psalms and the Westminster Assembly's Directory for Public Worship
While the DPW is the main emphasis below, the
FPCG does explicitly consider the “singing of psalms” to be one of the "Ordinances in a particular Congregation". Under the 9th head under the 9th rule in the "Rules for Ordination", we are told that "singing of a psalm" is to conclude an ordination service.