God commanded to keep the Sabbath day holy and appointed it as the fourth of the Ten Commandments.
“Remember the Sabbath day by keeping it holy.” Exodus 20:8
The Sabbath day is a memorial of God’s great work of creating the heavens and the earth.
God’s people must keep the Sabbath day holy according to God’s will. God distinguishes who His people are by whether they keep the Sabbath day 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. This is evident through the record of Jesus’ resurrection.
When Jesus rose early on the first day of the week (Sunday, TEV)… Mark 16:9
Christians worldwide celebrate Jesus’ resurrection on Sunday, the first day of the week. Since the first day of the week is Sunday, the seventh-day Sabbath is Saturday without a doubt. Jesus and the apostles, who followed His example, worshiped God in spirit and in truth on Saturday, the Sabbath.
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 throughout the Apostolic Age, was changed to Sunday worship. The law of God was changed by the political power of the Roman Emperor Constantine when he declared the law of Sunday worship in A.D. 321. As a result, churches today worship on Sunday. However, the Church of God, established by Jesus, keeps the Sabbath day on Saturday, which is the law of God. The law of Jesus, the Sabbath, is engraved on the hearts of the members of the Church of God.