The Christians’ gathering on the first day of the week was entirely different from the Jewish Sabbath which was still widely observed by the Jews at the time.
First and foremost, it was a voluntary act. There was no prescription at all to begin with. The first reference to a coming together of Christians is in Acts 2. Here we are told that they “continued daily with one accord in the Temple,” v.46. They were there not because they heeded a command. We are simply told that the disciples continued steadfastly in “the Apostles’ doctrine, fellowship, breaking of bread, and prayers,” v.42.
The first reference to a coming together of the disciples on the first day of the week is in Acts 20.7. Acts 20.7 records the gathering of the disciples at Troas on the first day of the week “to break bread.” The way the “coming together of the disciples to break bread” was described indicates it was a normal occurrence. Here Apostle Paul preaches.
The other reference to a first day of the week gathering is in 1 Cor.16.1. Here, Apostle Paul gives instruction to the church, “concerning the collection for the saints,” for them to do it on the first day of the week. It is noteworthy that the practice of coming together on the first day of the week was already widespread at this time. This is clear as Paul’s instruction to the Corinthians was merely a reiteration of his instruction to the churches in Galatia, “As I have given instruction to the churches in Galatia, so do ye also.” It is not unreasonable to imply that this was the prevailing practice among the churches then.
Thus, aside from the breaking of bread, a collection was gathered as the disciples came together on the first day of the week. There was also (at least on one occasion in Troas) preaching/teaching.
Three instances make the first day of the week stand out. First, the risen Jesus met with his disciples twice on the first day of the week — first, on the day of the resurrection itself; then the following week. What was intended to be the retreat of fearful, cowardly disciples turned out to be the first coming together of disciples for Christian worship. It became a time of meditation, reassurance, and empowerment for these first witnesses.
Secondly, the day of Pentecost in Acts 2, although special to the Jews, was made uber-special to Christians because it was the day the Holy Spirit was first poured out (Acts 2.17) and appeared in “a mighty rushing wind and flaming tongues as of fire” (Acts 2.3-5.) It was also the first day of the week.
And thirdly, John describes a certain “Lord’s day” in Revelations. There he says, “I was in the Spirit on the Lord’s day,” and from then on began seeing visions, that eventually became The Revelations. This phrase, the Lord’s day, is generally recognized as referring to the first day of the week, the day when the Lord Jesus rose from the dead and appeared to them.
This is, by and large, the reason I believe Christians gather together and meet for worship on the first day of the week, ie, Sunday. Not because it is the Sabbath day, but because it is the Lord’s day. The belief that the Lord’s day and the Sabbath command have no vital connection, aligns me with NCT thought.
But this does not lay down a prescription, ie, for Sunday worship. What began by the liberty of the (S)spirit, cannot degenerate into a law of the flesh. Sunday worship, although desirable and most natural, is not absolute.
This was exemplified in Acts 2.46a. Here we are told that the first Jewish converts (disciples) “continued daily with one accord in the Temple.” They met daily. And they met according to the liberty of the (S)spirit, not according to the bondage of the flesh. There are other recorded gatherings of disciples in the Book of Acts but we are not told that these were invariably on the first day of the week. There are no other records that the disciples came together to break bread except in Acts 20.7. There are also no other texts that indicate the disciples came together for the collections on the first day of the week except in 1 Cor.16.1, 2, referring to both the church in Corinth and the churches in Galatia.
Sunday worship is desirable and natural, being commemorative of the day Jesus rose from the dead and appeared to his disciples. But Friday is equally an acceptable day of worship, as no specific day was prescribed or commanded in Scriptures to be the day of worship for the NT church.
“God is Spirit: and they that worship him must worship him in spirit and in truth,” John 4.24.