God commanded us to keep the Sabbath day, the memorial day of God the Creator. It is a day of rest, but first and foremost it is a day to commemorate God’s creation of the heavens and the earth. God distinguished the Sabbath day and appointed it as the fourth of the Ten Commandments.
“Remember the Sabbath day by keeping it holy.”Exodus 20:8
God’s people must keep the Sabbath holy according to God’s will. God distinguishes between His people and those who are not, through whether they keep the Sabbath or not (Eze 20:11–17; Isa 56:1–7).
Then, what day of the week is the seventh-day Sabbath?
The Bible testifies that the Sabbath is Saturday, through the record of Jesus’ Resurrection Day.
When Jesus rose early on the first day of the week (Sunday, TEV)…Mark 16:9
The first day of the week, on which Jesus was resurrected, is Sunday. That’s why Christians worldwide celebrate Jesus’ resurrection on Sunday. Since the first day of the week is Sunday, the seventh-day Sabbath is Saturday without a doubt. That’s why Jesus and the apostles who followed His example worshiped God in spirit and in truth on the Sabbath—Saturday.
He [Jesus] went to Nazareth, where he had been brought up, and on the Sabbath day he went into the synagogue, as was his custom….Luke 4:16
As his custom was, Paul went into the synagogue, and on three Sabbath days he reasoned with them from the Scriptures….Acts 17:2
The Sabbath day, which had been observed until the Apostolic Age, was changed to Sunday worship as the Roman Emperor Constantine declared the Sunday law in A.D. 321. The law of God was changed by the political power of the Roman emperor. As a result, all the churches worship on Sunday today. However, the Church of God which Jesus Himself established keeps the Sabbath day, the law of God. It is because the words of Jesus, who wants us to be saved, are engraved on the hearts of the members of the Church of God.