What day of the week was the day of Pentecost falling on in Acts 2? Was it Saturday or Sunday? Or some other day?
There is not full agreement among different people. According to the People's New Testament it fell on a Sunday (50 days after Christ rose from the dead) and this seems to make sense to me because the death, burial, resurrection, and blessing of the Sprit all have a meaningful relationship with existing Jewish feats.
Pentecost, one of the three great annual festivals of the Jews, lasted only one day, was on the fiftieth day from the morrow after the passover Sabbath (Le 23:15-22). The Savior, crucified on Friday, was in the tomb on the passover Sabbath, and rose on Sunday, the day from whence the count began. The Sunday following would be the eighth day, and the fiftieth day would fall on Sunday, the first day of the eighth week. Hence, the ancient church observed Pentecost on the first day of the week. For fuller discussion, see Meyer, Howson and Milligan on this passage. All agree that Pentecost come on Sunday. Pentecost was the feast of the grain harvest, and was also held by the Jews to be the anniversary of the giving of the law (Ex 23:16 34:22,23). People's New Testament
I agree with the People's New Testament calculation partly because it matches so well with the symbolism of the events, which seems to be a biblical way of events naturally occurring. Sometimes when we get deep into the nifty gritty about Jewish things, such as this, I prefer to find a source that Jewish Christians support as they are more aware of the Laws of Moses then regular Christians are (although not always of course).
From a Jewish Christian site I found an excellent article on the subject explaining why it fell on a Sunday and why objections to this argument are not well founded:
The fulfillment of these feasts is striking. Jesus died the Friday of Passover week and had to be buried hastily before sunset, which was when the Sabbath began. His body remained in the borrowed sepulchre throughout the Sabbath day, but on that Sunday morning, when the priest was to offer the First Fruits offering in the Temple, Christ arose from the dead, the first fruits of them that slept (I Cor. 15:20).
For forty ensuing days, the Lord appeared to His disciples in His resurrection body, and then ascended into Heaven. Ten days later, the Sunday of the Feast of Pentecost, the Holy Spirit descended upon the believers in Jerusalem and created the ekklesia, the called out body of Christ, the church. These fulfillments were obviously no coincidence, but were part of the overall plan and purpose of God in verifying the powerful meaning of the death and resurrection of Christ, and the establishment of the new body of believers. (Thomas S. McCall)
The answer to this question is found in the Hebrew Bible--the day was Sunday. In order to understand the parallel, one must assume and then accept the Scriptures with the PLAIN and NORMAL understanding of its own words and meanings.
In other words, the VERY SAME DAY that the Mosaic Covenant was inaugurated to the nation of Israel on Sinai (Sunday) was the VERY SAME DAY that the New Covenant was announced to the nation of Israel (Sunday). The timing was exactly 50 days from the day as mentioned in Leviticus 23:16.
Thus in the former case, the law of God was written on stones; in the latter, the law of God was then written on hearts. In the former case the Feast of First Fruits marked the blessing of water from heaven (that precipitated abundant crops); in the latter case, this water from heaven was eternal life (that precipitated the "first fruits of the Spirit" mentioned in Romans 8:23). Please click here for an overview depiction to compare and contrast the concepts and the respective timelines concerned.
The parallels are remarkable (and breathtaking) when we assume and then accept the Scriptures with the PLAIN and NORMAL understanding of its own words and meanings.
In summary, there is no academic sophistry here--"Pentecost" thus occurred on a Sunday as we view the parallels from the Hebrew Bible.
The existing answers seem far too complicated. There really isn't even any need to bring anything from the New Testament into it.
Pentecost, of Shavuot, is defined in the Old Testament in the Book of Leviticus:
And he shall wave the sheaf before the LORD, to be accepted for you: on the morrow after the sabbath the priest shall wave it. — Levitcus 23:11
And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete: Even unto the morrow after the seventh sabbath shall ye number fifty days; and ye shall offer a new meat offering unto the LORD. — Leviticus 23:15–16
And ye shall proclaim on the selfsame day, that it may be an holy convocation unto you: ye shall do no servile work therein: it shall be a statute for ever in all your dwellings throughout your generations. — Leviticus 23:21
On the day after the first weekly sabbath following the annual Passover sabbath, a priest is to make a wavesheaf offering of the firstfruits of the spring harvest. The first day after a weekly sabbath is what we now call Sunday.
Then, starting from that day, 50 days are to be counted, and that day, which will also be a Sunday, is to be Shavuot, or Pentecost. ("Pentecost" comes from the Greek word for 50.)
So that Pentecost, and all Pentecosts, are always on a Sunday (more specifically, from sunset on Saturday evening until sunset on Sunday evening).
(Some people have a tradition of always celebrating Shavuot on the 6th day of the month of Sivan, by interpreting "sabbath" not as the weekly sabbath but as the first day of Passover. But given the instructions in Leviticus, that doesn't make sense. If it always occurs on the same date, there wouldn't be any need for the requirement to count 50 days.)
For those concerned with New Testament meanings, the "wavesheaf" ritual symbolized Christ being offered to Heaven as the firstfruit of God's harvest on the Sunday after his resurrection.
Pentecost (fiftieth day) is derived from one of the two national languages of Cyprus. This is how the term Pentecost is used in the so-called Maccabee Bible, because the festival was celebrated fifty days after the Passover celebrations. It is also well known that the Jewish Scriptures were written in the Hebrew language, but what is not apparently well known is that the Jews themselves were the first ones to translate the Hebrew Bible into Greek, while they were living in Africa. The translation was done over two hundred years before the birth of Christ and is still being used to this day. It is this version, popularly known as the Septuagint (LXX), that first associated the term Pentecost with the feast mentioned in Leviticus 23:16. A literal rendering of this text reads “you shall number pentekonta days”; here the verb ‘number’ is related to our English word ‘arithmetic’ and of course the numerical adjective pentekonta is the term for fifty. In Second Maccabees 12 we have an interesting account of a Jewish battle against their enemies. In verse 31 we read about what happened before this skirmish: “and so they came to Jerusalem, to the feast of weeks,” and we also read in the following verse “And after . . . Pentecost they went . . . against . . . the governor of Idumea.” The verses are interesting because they give us two of the names of this great Jewish festival—the one preferred by Jews themselves living in and around Jerusalem and the other which became popular among the people of God living in the diaspora, that is, the Hag Shavuot or feast of weeks found in, Deuteronomy 16:10. The term feast of weeks refers primarily to the seven weeks or forty nine days between the Jewish Passover and the fiftieth day of special celebration that normally falls on a Sunday. The same event is also called the feast of first fruits, because Pentecost was originally a harvest festival. For a number of orthodox Jews it is still commemorated as such. Whereas it is a one day celebration for Jews today, the Orthodox Christians on the island of Cyrus do so over three days. Day one is dubbed Trinity Sunday, day two, Spirit Monday, and the Tuesday, the Day of the Trinity.
Christianity in the west for the most part seldom highlights Pentecost, the day the church became the bride of Christ. But what has left an indelible mark on the West is the spiritual awakening of the early twentieth century known has the Pentecostal movement. The movement itself is heavily indebted to Luke’s account of the coming of the Spirit recorded in Acts 2. While Pentecostal Christians cannot claim all the credit for the fifty-percent of Jamaicans who testify that the Spirit of God is living in them, it would be foolhardy and unkind to ignore their contribution to this aspect of authentic nation building; for without it, there shall no flesh be saved alive! We thank God, then, for the first Christian Pentecost and the harvest of souls then and now, as well as the three thousand one hundred and twenty who received the Spirit on that memorable day. Shalom.
Though Sunday is not the true day of rest. It's Saturday according to the Law. But when Christ came, he fulfilled the demands of the sabbath day on our behalf. So if we worship on a Sunday, rest from the 6 days work is not the issue. Three remarkable events occurred on Sunday. 1-the light of Christ that God commanded to shine came to be on the 1st day of Creation. Remember the sun, moon and stars were created on the fourth day (Genesis 1:14-19). 2- Christ defeated the power of death when he resurrected on Sunday, the 1st day of the week. 3- the promise that God made to Abraham was fulfilled on Sunday, the 1st day of the week when Christ's Helper, the Holy Spirit, came down to live in us. That was 50 days after his resurrection. If you count 50 days starting with Easter Sunday, you will land on a Sunday.