Q. How early in Church history was Mass celebrated on Sundays?
A. The early Christians began meeting for worship on Sundays (the first day of the week) instead of Saturdays (the seventh day, the “Sabbath,” as prescribed in the Law of Moses) because that was the day on which Jesus rose from the dead. They called it “the Lord’s Day.” Some denominations that insist on Saturday Sabbath worship claim that this change took place after the Roman Emperor Constantine meddled in Church affairs in the fourth century. But Scripture and several early Christian writers provide sufficient evidence to the contrary.
In Scripture, St. Paul says the first believers came together on the first day of the week (1 Corinthians 16:2), as does the Book of Acts (20:7). The latter notes that it’s the day on which believers came to “break bread,” which was how the early Christians described the Eucharist. The Book of Revelation also refers to “the Lord’s Day” (Revelation 1:10).
As for other ancient witnesses to Sunday worship, St. Ignatius of Antioch wrote soon after the composition of St. John’s Gospel (sometime before the year 117): “We are no longer keeping the [seventh-day] Sabbath, but the Lord’s Day” (Epistle to the Magnesians, 9, 1).
The early Christian theologian named Origen reported in the late 100s: “The Word [Christ] has moved the feast of the Sabbath to the day on which the light was produced and has given us as an image of true repose, Sunday, the day of salvation, the first day of the light in which the Savior of the world, after completing all his work with men and after conquering death, crossed the threshold of heaven, surpassing the creation of the six days and receiving the blessed Sabbath and rest in God” (Commentary on Psalm 91).
The ancient text called the Didache may be as old as some of the New Testament books, though some think it might have been written a few decades later. Either way, this book is quite early, and it also says that Christians should meet together on “the Lord’s Day” to celebrate the Eucharist. In addition, the Epistle of Barnabas, written about the year 130, plus a work by St. Justin Martyr, about the year 205, make similar references that are even more explicit that the day is Sunday, not Saturday.
We should note that not only was Jesus raised from the dead on Sunday, the first day of the week (see Matthew 18:1; Mark 16:9; Luke 24:1; John 20:1, 19). All His recorded appearances after His resurrection occurred on Sunday as well (see John 20:19, 26), including His last recorded appearance, to St. John on the Isle of Patmos (see Revelation 1:10). In addition, Christ sent His Holy Spirit to the Church on the Day of Pentecost, which was also a Sunday. By choosing the first day of the week for His resurrection and His post-resurrection appearances, not to mention the “birthday” of the Church, Christ made the first day of the week forever the “Lord’s Day.” PT