A note from Naphtali Press about why they were historically retained:
“Generally speaking the churches were curtailing the calendar of old pretended holy dasy more and more but magistrates tended to view things differently, either for ill or practical reasons (they were the only days off for servants is about the best reason you can find) reimposed or retained them. By the time next century of the Nadere Reformatie when such things were being re examined, I guess it was basically too late for significant change. I cover some of this in a look at Calvin in the introductory piece I wrote to a translation of two of his letters that will appear in the 13th issue of The Confessional Presbyterian, due out in about two weeks.
“In Translatiōne: John Calvin’s Letters to the Ministers of Montbéliard (1543–1544): The Genevan Reformer’s Advice and Views of the Liturgical Calendar,” The Confessional Presbyterian 13 (2017 forthcoming): 198-220.
Demarest puts the best spin from their perspective on it.
At first it was clearly the intention to abolish these days entirely. Then it was deemed better (as the people continued to take them for holidays), to turn them to a good account by the holding of religious services, and finally their observance was enjoined, doubtless on the ground of edification. Probably the magistrates, who are continually referred to as having authority in the matter, did not, for reasons springing out of the circumstances of the times, and the genius and habits of the people, deem it expedient to abolish, them. While they continued by authority, the Church, rightly aimed to make them promotive of piety.”
David D. Demarest, History and Characteristics of the Reformed Protestant Dutch Church, 2nd ed. (New York, Board of Publication of the Reformed Protestant Dutch Church, 1856), 175.
Source: https://puritanboard.com/threads/the-dutch-reformation-and-special-days.93902/, Comment 2
“Experimental preaching must in the first place be discriminatory preaching. Discriminatory preaching defines the difference between the Christian and the non-Christian. Discriminatory preaching is the key by which the kingdom of heaven is opened to believers and shut against unbelievers. Discriminatory preaching promises the forgiveness of sins and eternal life to all who by a true faith embrace Christ as Savior and Lord; it likewise proclaims the wrath of God and eternal condemnation as God’s judgment upon the unbelieving, unrepentant, and unconverted. Such preaching teaches us that unless our religion be experiential, we shall perish-not because experience itself saves, but because the Christ who saves sinners must be experienced personally as the rock upon which the house of our eternal hope is built (Matthew 7:22-27; 1 Corinthians 1:30; 2:2).”
Source: https://puritanboard.com/threads/discriminatory-preaching.93641/, Comment 2
Scott Aniol, Chair of the Worship Ministry Department of Southwestern Baptist Theological Seminary and non-EP proponent:
If you were in Ephesus when Paul’s letter arrived, and you had a Bible in your church, it was a Septuagint. As you browsed through the Book of Psalms three terms would keep appearing in the titles and you would be quite familiar with them – psalmos, humnos and ode. In 67 Psalms the word psalmos is found eg Psalm 23; in 6 titles the word humnos appears eg Psalm 8; in another 35 Psalms ode is in the title eg Psalm 45. Furthermore, in 12 Psalms the words psalmos (psalm) and ode (song) are found together in the title e.g. Psalm 65, and in 2 titles psalmos (psalm) appears with humnos (hymn) eg Psalm 6. If you had studied the title of Psalm 76 all three terms are found in the Septuagint title, ‘For the end, among the hymns, a psalm for Asaph; a song for the Assyrian’. The Ephesian Christian would know that one Psalm could be a psalm and a song, or even a psalm and a song and a hymn together. All three terms were found in the titles of the Psalms and even in the title of one composition in the Book of Psalms. Paul exhorted them in biblical terms they were familiar with.
Source: https://puritanboard.com/threads/singing-inspired-songs-ep-answers-only.93584/page-2, Comment 31
The basic premise is that God commands believers to hold to the principles of worship He sets forth for the age in which they live. When God commands the building of the tabernacle and institutes sacrifices in this specific location, He changes worship in Israel. The people are not permitted to use the standards of worship previously followed by Abraham. When David adds singing of the Psalms and additional musical instruments to worship in the tabernacle and in the temple by the command of God, the people are not permitted to revert to the more simplified worship under Moses. Similarly, the people living in the time of David and Solomon could not look ahead and adjust their worship to conform to the new age ushered in by Messiah. They were not permitted to forsake principles of worship ordained by God for their time. In like manner, believers today are required to maintain the standards of worship God gives them for this present age. It is not their prerogative to appropriate into the worship of today aspects of worship from another age, whether earlier or later. This argument is another way of stating the regulative principle of worship.
Source and read more: https://rpcnacovenanter.wordpress.com/2017/08/23/objections-to-exclusive-psalmody-pt-2-sing-a-new-song/
Rev. Henry Cooke of Ireland in the first preface to The True Psalmody:
“Now, while I set not up my own convictions as a rule or measure of the consciences of others, I cannot fail to pity those who can find, as they assert, so little of Christ in the inspired psalmody of the Bible, that they must seek and employ an uninspired psalmody as exhibiting Him more fully. Our Lord Himself found Himself in the psalms—(Luke 24:44, 45)—and thereby “opened His disciples’ understanding, that they might understand the Scriptures.” Surely what was the clearest light to their eyes, should be light to ours. And, truly, I believe, there is one view of Christ—and that not the least important to the tired and troubled believer—that can be discovered only in the Book of Psalms—I mean His inward life. No eye-witness of the outward man—though an inspired evangelist—could penetrate the heart. But the Spirit who “searcheth the deep things of God,” has, in the psalms, laid open the inmost thoughts, sorrows, and conflicts of our Lord. The Evangelists faithfully and intelligently depict the sinless Man; the psalms alone lay open the heart of “the Man of sorrows.” The most pious productions of uninspired men are a shallow stream—the Psalms an unfathomable and shoreless ocean.”
Source: https://puritanboard.com/threads/singing-uninspired-songs-non-ep-answers-only.93520/page-3, Comment 72
See also Comment 85 of the same thread
Behold, they paint and portray Jesus Christ, who (as we know) is not only man, but also God manifested in the flesh: and what a representation is that? He is God’s eternal Son in whom dwells the fullness of the God head, yea even substantially. Seeing it is said, substantially, should we have portraitures and images whereby only the flesh may be represented? Is it not a wiping away of that which is chiefest in our Lord Jesus Christ, that is to wit, of his divine Majesty? Yes: and therefore whensoever a Crucifix stands mopping & mowing in the Church, it is all one as if the Devil had defaced the son of God. (Sermon on Deuteronomy, 23 May, 1555)
Source: https://puritanboard.com/threads/images-of-jesus.93678/page-2, Comment 42
“It is not lawful to have pictures of Jesus Christ, because his divine nature cannot be pictured at all, and because his body, as it is now glorified, cannot be pictured as it is, and because, if it do not stir up devotion, it is in vain; if it do stir up devotion, it is a worshipping by an image or picture, and so a palpable breach of the second commandment.”
(Vincent, Exposition of the Westminster Assembly’s Shorter Catechism.)
Source: https://puritanboard.com/threads/images-of-jesus.93678/, Comment 16
In the spiritual worship of the gospel the whole blessed Trinity, and each person therein distinctly, do in that economy and dispensation wherein they act severally and peculiarly in the work of our redemption, afford distinct communion with themselves unto the souls of the worshippers…There is no act, part, or duty of gospel worship, wherein the worshippers have not the distinct communion with each person in the blessed Trinity…
This is the general order of gospel worship the great rubric of our service. Here in general lieth its decency, that it respects the mediation of the Son, through whom we have access, and the supplies and assistance of the Spirit, and a regard unto God as a Father. He that fails in any one of these, he breaks all order in gospel worship. If either we come not unto it by Jesus Christ, or perform it not in the strength of the Holy Ghost, or in it not unto God as a Father, we transgress all the rules of this worship. This is the great canon, which if it be neglected, there is no decency in whatever else is done in this way. And this, in general, is the glory of it.
(from “The Nature and Beauty of Gospel Worship,” in The Works of John Owen, volume 9, pp. 56-7).
Source: https://puritanboard.com/threads/worship-must-be-trinitarian.93142/, Comment 1
“When all this is said and done, it may be useful to highlight that none of this is mean to discourage the writing or singing of songs which are in praise of God. Many such songs — for example, ‘When I Survey the Wondrous Cross’ — have found their way into the affections of many of the Lord’s people and, providing the content is honouring to God, the writing of such songs and their performance can be seen as the valid exercise of a valid gift. However, the questions at issue concern when, where and how such songs are to be used.
After all, it is the Reformed understanding of worship that worship takes place when we draw near to God by calling upon his name. This worship consists of an act, or a series of acts, in which God speaks to us (in reading, preaching, and sacraments) and in which we present our offerings to God (in song and prayer – sometimes accompanied with vows and fasting). It is also the historic Reformed understanding that nothing is to be offered to God as worship without his explicit appointment – and that the songs which he has appointed which he has appointed to be offered in the context of worship are the Psalms!”
– Kenneth Stewart
Source: https://puritanboard.com/threads/ep-only-in-corporate-public-worship.93273/, Comment 3
“We grant also, that any private Christian, who hath a gift to frame a spiritual Song, may both frame it privately, for his own private comfort, and remembrance of some special benefit, or deliverance. Nor do we forbid the private use of an Instrument of Musick therewithall: So that attention to the Instrument, does not divert the heart from attention to the matter of the Song.”
– John Cotton
Source: https://puritanboard.com/threads/ep-only-in-corporate-public-worship.93273/, Comment 3