Observance of the Sabbath
The Sabbath goes back to the creation of the world, when it was ordained by God for all the ages, as a basic structure of human life, along with marriage and labor.
To remember the Sabbath means to uphold its distinctiveness from other days of the week. This is a precept of the enduring moral law, set down in the ten commandments. When those ten words were first given, observance of the Sabbath was grounded in a recognition of what God had done in bringing the world into existence. When the ten commandments were reissued in Deuteronomy, a further reason was given for Sabbath observance, for now the people were exhorted to consider that God had redeemed them from bondage. These two considerations were summed up in the ninety-second Psalm, designated as intended for the Sabbath, when worshippers were called to reflect on mighty works of all kinds done by God. The Sabbath is a day to worship God for what he has done.
The greatest of the acts of God in redemption are the death and resurrection of his Son. The Lord's Supper and the Lord's Day are the commemorative institutions which place those two acts in the center of God's worship. With the inauguration of the New Testament, the Sabbath was moved from the seventh day, where it had been placed at the culmination of the creation week. Now it takes its position on the first day of the week, signaling the beginning of the new creation brought in by the resurrection of Christ.
Christ noted that the temple labor of the priests on the Sabbath day was blameless labor, because what is required in the observance of the Sabbath is not a cessation of all activity, but rather an activity distinct from the ordinary business of the other days of the week. While the other six days are left to us for our employment and recreation, the Sabbath is a whole day set apart for the worship of God.
The New Testament also speaks of pilgrims in this world awaiting a Sabbath-keeping in the world to come. Our present Sabbath observance is a pledge that there is a future rest from the preoccupations of this world. Our life now should not be an uninterrupted routine. God has appointed that it be punctuated every seven days with a pause which serves to remind us that this life will eventually give way to an eternal Sabbath of worshipping God in the beatific vision of his glory and love.
James MacGregor: The Sabbath Question