All right, let's look at the Bible itself. What day of the week did the early Christian church worship on, when the church was lead by the Apostles?
On the Sabbath. This can be established by both the Bible, writings hundreds of years after the Resurrection and by the Roman Churches edicts against it hundreds of years later.
1) On the Sabbath:
First it must be established that Pentacost came *before* the conversion of Saul and *after* the Resurrection of Christ. This happened just as it should, on the 50th day after the Sabbath that occurred during the Feast of Unleavened Bread. This is why the disciples had to WAIT after Christ appeared to them over 40 days. Pentacost had "not yet come" and it certainly wasn't on the day Christ rose from the dead:
Acts 1:3,4 Jesus is showing himself for 40 days after His Resurrection, and tells them not to depart from Jerusalem, but wait for the promise of the Father.
Acts 2:1 The day of Pentacost (the 50th day) has "fully come". Yes, this was what we call Sunday.
From Acts chapters 2-9, the body of believers increases, and there is much preaching from Peter - but no change in the day of worship, and no preaching of a change in the day. In fact, there is not one place in Acts where you can find such an important teaching on the change in the day of Worship. There is not a hint of it, not one iota - and *it would have been noticed* - because to the Jews the Sabbath was VERY important. It was the heart of the covenant with God. Yet, there is absolutely no preaching on a change of God's Holy Day.
Now the church is growing, and Saul is getting annoyed:
Acts 9:1-2
And Saul, yet breathing out threatenings and slaughter against the disciples of the Lord, went unto the high priest, 2 And desired of him letters to Damascus to the synagogues, that if he found any of this way, whether they were men or women, he might bring them bound unto Jerusalem.
Saul is persecuting early Christians *in the synagogues*, which means that the early believers were still keeping Sabbath, along with their unbelieving Jewish bretheren.
Acts 9:20 After his conversion, Saul/Paul preaches Christ *in the synagogues*, which means he is preaching on the Sabbath.
Acts 13:14+ Paul and company preach on Sabbath
THE GENTILES entreat Paul to Preach to them the NEXT SABBATH:Acts 13:42,44
Acts 16:13 Again on the Sabbath
Acts 17:2 Paul reasons with them out of the Scriptures 3 Sabbaths
Acts 18:4 Still reasoning every Sabbath
Throughout the entire book of Acts, there is only one place where you can say the disciples met on Sunday(at least from most bibles), and that is Acts 20:7
And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight.
The phrase translated "first day of the week" is this
" Mia twn Sabbatwn ". It is used in Matthew, Luke and John to describe "the first day of the week" in the Resurrection passages.
"Mia" means "one", it doesn't mean "first". It is the same word used here:
"one of the least of these commandments"
"one of the maids" Mark 14:66
"one city" (or, a certain city) Luke 5:12
"one day (or, a certain day) Luke 5:17
These are just 4 of 72 times in the NT alone where "mia" means "one" or "a certain one".
The word for "first" is "protos", and it likewise has a specific meaning, and a very specific usage in both the NT and the Septuagint.
Mia twn Sabbatwn literally translates "one of the Sabbaths". But because "mia" is feminine and "of Sabbaths" is Neuter - the word "day" (in feminine) has been added to the text. So then, we have "one day of the Sabbaths".
"Day of the Sabbaths" is used in the following places to describe the Sabbath day:
Luke 4:16, Acts 13:14, Acts 16:13
The phrase translated "Sabbath day" in the Greek of these passages is "hemera twn sabbatwn" -" day of the Sabbaths"
The word for "week", btw, was known at the time. It was and still is "hebdomadas"(ebdomadoV) and is used in the Septuagint in Lev 23:15, and Deut 16:9. It is also used by Josephus here:
Antiquities of the Jews 3:252
Wars of the Jews 2:289
Wars of the Jews 4:99
Against Apion 2:175
And guess what? It's still used in modern Greek today.
ebdomadoV = "week" in modern Greek
Matthew Chapter 28 - Modern Greek Bible - Free Bible Software by johnhurt.com
Matt 28:1 (3rd line down, first word)
When the Holy Spirit came on the Church at Pentecost, Pentecost was a Jewish Festival before it was a Christian event. Pentecost was on a Sunday.
Christians had gathered for worship on a Sunday, having no idea that they would experience the coming of the Holy Spirit. Then the Holy Spirit chose to descend on the Church on Sunday, confirming their choice of that day of worship.
You are absolutely correct about Pentacost falling on a Sunday, but the whole meaning of the holy-day is lost when people substitute a once a year event for every first day of the week.
As for "confirming their choice on day of worship" - this is total nonsense. Pentacost was an annual holy-day that fell once a year, not a weekly event after the Sabbath.
Pentacost *is* and *was* an ANNUAL HOLYDAY. *Not* a weekly one. In every passage in Acts, the preaching and gathering of the disciples is on the Holy Sabbath.
When Jesus appeared to the disciples the first time, when they acknowledged Him how could they do this *without* the Holy Spirit? Over the next 40 days when He made multiple appearances - how could they believe *without* the Holy Spirit? Did Thomas not have the Holy Spirit when he exclaimed "my Lord and my God!" ??? (John 20:28)
What else is interesting about Pentacost? It falls right after 7, 7's. 7 in the bible is used for perfection and completeness, and the Disciples would still have been keeping the Sabbath up to Pentacost, counting Sabbaths, and when they preach *after* Pentacost, they are STILL preaching on the Sabbath!
2) I've already given some links above showing that many many Christians were still keeping Sabbath at least 500 years after the Resurrection of Christ! Here are some more:
Taken from "From Sabbath to Sunday" by Sam Bacchiocchi
Pope Innocent I, about 417 A.D, wrote a decretal which became canon law that the church should absolutely not observe the sacraments on Friday or Saturday. Which reveals, of course, that up until this time, a lot of people did. Two contemporary historians, Sozomen (about 440) and Socrates (about 439) confirm this.
According to Socrates: "Although almost all churches throughout the world celebrated the sacred mysteries on the Sabbath of every week, yet the Christians of Alexandria and Rome, on account of some ancient tradition, have ceased to do this." (ibid. p. 196)
So as late as the fifth century, those who did not keep the Sabbath were in the minority of Christian churches. It is not saying too much to say that the Roman church was determined to inhibit Sabbath observance. They ordered fasting on the Sabbath and this practice continued among some until after 1000 AD. (ibid. p. 192)
3) That the Roman Catholic church issued a decree in AD 365 that no Christians shall keep the Sabbath shows that there were plenty of people that were doing this:
Council of Laodicia, AD 365: Christians must not judaize by resting on the Sabbath, but must work on that day, rather honouring the Lord's Day; and, if they can, resting then as Christians. But if any shall be found to be judaizers, let them be anathema from Christ.