First, let’s line up the usual suspects.
Did Rome do it?
If Rome changed the Sabbath to Sunday, it would only explain why Protestants and Roman Catholics worship on Sunday. It would not explain why Orthodox Christians worship on Sunday, and it certainly would not explain why Syriac, the Armenian, and Coptic Christians worship on Sunday, because they had very little contact with Rome until modern times. For example, the Armenian Apostolic Church does not celebrate Christmas, which originated in Rome in the fourth century. Instead, they celebrate the nativity of Jesus Christ on Epiphany. Rome could only have changed the day of worship before the fall of the Roman Empire, because after then communications weren’t good enough. However, during that period, Rome did not have much influence in the east.
Did the Emperor Constantine do it?
Constantine converted to Christianity after winning the battle of the Milvian Bridge. He wasn’t a very bright man and he did not have a coherent personal theology. After he became emperor, he reformed the tax system, passed laws protecting widows and orphans, donated money to churches, and sent his mother Helen to the Holy Land to preserve and restore all those sites that tourists visit even today. He passed a law that made all religions legal, and that ended the persecution of Christians. He convened and paid for the first ecumenical council in AD 325, but he was unable to understand the debates, let alone participate in them. He also changed the Roman week from ten days to seven days, so that Sunday, the Christian day of worship would always be a holiday. He did not make Christianity the state religion or do any of the other evil things often attributed to him—they were actually done by his successor, Theodosius, eighty years later. When Constantine instituted the seven-day week, he did it because Christians were already worshiping on Sunday and his purpose was to make it easier for them.
So who moved the Sabbath?
No one ever moved the Sabbath. In fact, if you look on page 283 of the Book of Common Prayer of the US Episcopal Church, you will find a service for Holy Saturday, the day before Easter Day. There is a prayer on that page that says, “O God, creator of heaven and earth: Grant that, as the crucified body of your dear Son was laid in the tomb and rested on this holy Sabbath, so we may await with him...”
When did worship on Sundays begin?
In the early centuries, Christians everywhere worshipped on Sunday. We know that from Christian writers who described ancient worship, such as Justin Martyr, who died in 157. All ancient churches, from Gaul to Armenia, had their main worship service on Sunday.
Why did ancient Christians worship on Sunday?
Sunday was the universal day of Christian worship because it is the day of the Resurrection, the day after the Sabbath, and the Feast of Firstfruits—which is why Paul calls Jesus’ resurrection the firstfruits of the resurrection (1 Corinthians 15:20). Since it is the first day of the week, it is also the eighth day of the previous week, the day of the new creation (the allusion in 2 Corinthians 5:17).
The Sabbath commandment does not require worship, it prohibits work. Worship can occur on any day. The synagogue originated during the Babylonian Captivity, not as a place of worship, but as an school to preserve Jewish heritage and religion in a foreign land.
In the first century, many Christians, both Jews and gentile “God-fearers,” continued to attend synagogue instruction on the Sabbath and then attended Christian worship on Sunday. Since the Roman week was ten days long at the time, Sunday didn’t always fall on the Roman weekend, so services were held before sunrise. In the 90s, the rabbis excommunicated the Christians and inserted wording into the synagogue liturgy that would make Christians very uncomfortable, even if they did attend. So we were left with just Sunday.
When Christianity became dominant in an area, it was common for larger churches to hold worship services on all days of the week.
Why do some people call Sunday the Sabbath?
The Sabbath is, of course, Saturday. As the Church grew and Christians came to outnumber Jews, there was talk of Sunday being like a Christian Sabbath. From there it was a short step to talk of Sunday as if it were the Sabbath. That’s not a bad comparison of the church and the synagogue. Sunday is not and it never has been the Sabbath.
How does one keep the Sabbath holy?
The word “Sabbath” is related to the Hebrew word for “rest,” and the primary duty of a Jew is to stop working on the Sabbath. Biblically, you keep the Sabbath holy by not working. In Orthodox Judaism, it is a sin to drive a car on the Sabbath, because the Law of Moses prohibits making fires on the Sabbath and cars have internal combustion engines—so driving a car amounts to making a series of little fires. Therefore, if you are an Orthodox Jew, and you live beyond walking distance of the synagogue, it is a sin to attend worship if you have to drive to get there.
Saturday is the Sabbath. Sunday is the Lord’s Day, because Jesus rested in the tomb on the Sabbath and rose on Sunday. Therefore the principal day of Christian worship has always been Sunday—until the 19th century when some Christians innovated the custom of worshiping on the Sabbath.
What’s a Christian to do?
The apostles had a meeting to decide which of the Jewish laws apply to non-Jewish Christians. Their decision is recorded in Acts 15:24-29. If you read it carefully, there is nothing in there about the Sabbath. Any modern Jewish rabbi would agree—the Sabbath law only applies to Jews. If you want to keep the Sabbath holy, you can follow Jesus’ example—you don’t have to go so far as to rest in a tomb, just do the resting part and abstain from work. Since Jesus rose from the grave on Sunday, that is the best day to celebrate it in worship.
However, there is no day of the week on which you must not worship. Your church can have its principal day of worship on Saturdays, if it likes. Your church could even have its principal day of worship on Tuesdays, for that matter. I admit, that would be a little odd, and it would be a break with the ancient church, but don’t let anyone tell you it is wrong. There is also nothing stopping you from worshiping every single day, and in fact I strongly recommend it. You can set up an oratory in a spare room or some other space and have personal or family devotions as often as four times a day using the Book of Common Prayer, other resources, or the Prayer Builder on this website.