Its a normal claim for any protestant to claim, “For the Christian, the Sabbath is observed on the Lord’s Day (Revelation 1:10). This day celebrates the resurrection of Jesus.”
The implication is that the biblical Sabbath, identified at Creation as “the seventh day” (Genesis 2:2, 3), was somehow changed to Sunday by the time the apostle John was imprisoned on Patmos, the place where he wrote the book of Revelation.
Most church historians agree that the change from Saturday to Sunday is not biblical, but ecclesiastical and political. God predicted a religious power would attempt to change His law (see Daniel 7:25). While it is honorable to celebrate the glorious resurrection of Christ, keeping Sunday is not how the Bible tells us we should acknowledge this event. The Bible teaches that baptism symbolizes the resurrection of Christ (see Romans 6:1–6). The symbol of Jesus’ resurrection is not found in worshiping on Sunday, the day of the sun adopted from pagan Rome’s sun worship.
A related argument about this supposed change is found in the false separation between a Jewish Sabbath and a Christian Sabbath. One writer says, “On the Gregorian calendar, which the Western part of the world operates on, for Christians, Sunday, or the Sabbath Day, at one time or another was considered sacred and holy.” But the change from the Julian calendar to the Gregorian calendar did not alter the days of the week. Saturday is still the seventh day.
In both the Old and New Testaments, God associates the Lord’s Day with the seventh day of the week. In Exodus 20:10, God told His people directly, “The seventh day is the Sabbath of the Lord your God.” Throughout the rest of the Bible, there was no question that the Lord’s day was the seventh-day Sabbath. Through the prophet Isaiah, God told His followers to “call the Sabbath a delight, the holy day of the Lord honorable” (Isaiah 58:13). And Jesus Himself, who consistently kept Sabbath on the seventh day of the week (Luke 4:16), stated, “The Son of Man is Lord even of the Sabbath” (Matthew 12:8).
The Lord’s day has always been and always will be Saturday, the seventh day of the week.