I want to clarify something. Maybe I was unclear on my above post.
There is nothing wrong with worshipping God on any day. Today (some call it "Good Friday"), I thank God for his death on the cross and resurrection from the dead. There is nothing wrong with having a church service today, or tomorrow, or the day after that (the Sabbath is required). I will worship God on Christmas, and Easter too (Lord willing).
However, setting certain days aside as "holy days" are strictly forbidden and can not be observed AS SUCH without sinning. God has set ONE day aside as Holy, and does not give us the right or freedom to do so with others. Easter week is considered "Holy Week."
From the Westminster Assembly's Directory for Public Worship:
Festival days, vulgarly called Holy-days, having no warrant in the word of God, are not to be continued.
G.I. Williamson includes Good Friday in his list of "holy days" NOT to be observed (quoted from a
link from Matt's website)
"What Jesus desires of us is not the observance of things He did not command, but the things He did command. 'Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: Teaching them to observe all things whatsoever I have commanded you' (Matt. 28:19,20). This is what the Apostles did. They taught the whole counsel of God (Acts 20:27). It did not include Christmas, Good Friday, or Easter, because they were not part of the things commanded by Christ. So, the one who understands 'the true meaning of Christmas' (or Good Friday, or Easter) is precisely the one who realizes that they are human inventions. And in order to honor Christ as the only King and head of the church, such a person will not observe these man-made additions to what our Lord commanded. A person such as this may be out of step with a very popular custom. The important thing is that he will be in step with Christ and the Apostles."
G. I. Williamson, On the Observance of Sacred Days, (Havertown: New Covenant Publication Society, n.d.), pp. 9-10.
also here
Christmas, Good Friday, and Easter are Romish sacred days. By this we mean that they have their source in Roman Catholic tradition, rather than in Scripture. . . . [T]here have been times in the history of the Reformed churches when the truth on the subject of sacred days received reverent attention. Already, before John Calvin arrived in Geneva at the time of the great Reformation, the observance of Romish sacred days had been discontinued there. This had been done under the leadership of Guillaume Farel and Peter Viret. But Calvin was in hearty agreement. It is well known that when these traditional days came along on the calendar, Calvin did not pay the slightest attention to them. He just went right on with his exposition of whatever book of the Bible he happened to be expounding. The Reformers, Knox and Zwingli, agreed with Calvin. So did the entire Reformed church of Scotland and Holland. At the Synod of Dort in 1574 it was agreed that the weekly Sabbath alone should be observed, and that the observance of all other days should be discouraged. This faithful Biblical practice was later compromised. But that does not change the fact that the Reformed churches originally stood for the biblical principle. The original stand of the Reformed churches was Scriptural. That is the important thing. --G. I. Williamson (minister, Orthodox Presbyterian Church), On the Observance of Sacred Days (n.d.).
The Waldenses did not observe Good Friday for the same reason according to the same source:
[The Waldenses] contemn all approved ecclesiastical customs which they do not read of in the gospel, such as the observance of Candlemas, Palm Sunday, Good Friday, and the feast of Easter. . . . --William Sime, History of the Waldenses (1827).
My concern is that most churches today HAVE continued these Romish traditions in the name of worshipping God according to the imaginations of men.
Again, my concern is NOT with having a church service on another day besides the Sabbath (or even a church service on good friday). It is the celebration of the Catholic "holy day" of good friday that is wrong, and it is my opinion that most church services on this day, do just that.
Certainly the Westminster Divines allowed for days of thanksgiving etc., but it was not their intention to observe the Romish "holy days." John Flavel (a Westminster Divine) had this to say:
Q. Is there any other day holy besides this day [i.e., the Lord's day]? A. No day but this is holy by institution of the Lord; yet days of humiliation and thanksgiving may be lawfully set apart by men on a call of providence; but popish holidays are not warrantable, nor to be observed; Gal. 4:10. Ye observe days, and months, and times, and years. --John Flavel (Nonconformist minister, Dartmouth, England), An Exposition of the Assembly's Shorter Catechism (1692).
John Brown, of Haddington made this distinction between a "holy day" and a day of fasting:
Q. May the church appoint holy days, to remember Christ's birth, death, temptation, ascension, &c.?--A. No; as God hath abolished the Jewish holy days of his own appointment, so he hath given no warrant to the church to appoint any: but hath commanded us to labour six days, except when Providence calls us to humiliation or thanksgiving; and expressly forbids us to observe holy days of men's appointment, Col. 2:16; Gal. 4:10,11. Q. What is the difference between a fast day and a holy day?--A. The day of a fast is changeable, and esteemed no better in itself than another day; but a holy day is fixed to a certain time of the week, year, or moon, and reckoned better in itself. --John Brown, of Haddington (minister and professor, Associate [Presbyterian] Burgher Synod), An Essay Towards an Easy, Plain, Practical, and Extensive Explication of the Assembly's Shorter Catechism (1758).
Worship God everyday. Keep one HOLY day-the Sabbath.
Soli Deo Gloria