First of all, one must note that there are two kinds of laws in the Old Testament: moral precepts and ceremonial precepts. Christians believe that, through his suffering, death, and resurrection, Jesus has freed us from the observance of the ceremonial precepts.
The Sabbath law of the Ten Commandments includes both a moral precept and a ceremonial precept. Christians have been freed from the observance of the ceremonial precept of the Sabbath law, namely the observance of the specified Sabbath Day. However, Christians are still bound by the moral precept to worship God.
Jesus rose from the dead “on the first day of the week.” Because it is the “first day,” the day of Christ’s Resurrection recalls the first creation. Because it is the “eighth day” following the sabbath, it symbolizes the new creation ushered in by Christ’s Resurrection. For Christians it has become the first of all days, the first of all feasts, the Lord’s Day (he kuriake hemera, dies dominica) Sunday: We all gather on the day of the sun, for it is the first day [after the Jewish sabbath, but also the first day] when God, separating matter from darkness, made the world; and on this same day Jesus Christ our Savior rose from the dead.
Sunday is expressly distinguished from the sabbath which it follows chronologically every week; for Christians its ceremonial observance replaces that of the sabbath. In Christ’s Passover, Sunday fulfills the spiritual truth of the Jewish sabbath and announces man’s eternal rest in God. For worship under the Law prepared for the mystery of Christ, and what was done there prefigured some aspects of Christ: those who lived according to the old order of things have come to a new hope, no longer keeping the sabbath, but the Lord’s Day, in which our life is blessed by him and by his death.
The celebration of Sunday observes the moral precept inscribed by nature in the human heart to render to God an outward, visible, public, and regular worship “as a sign of his universal beneficence to all.” Sunday worship fulfills the moral precept of the Old Covenant, taking up its rhythm and spirit in the weekly celebration of the Creator and Redeemer of his people.
In short, the suffering, death, and resurrection of Jesus has ushered in the Everlasting Sabbath of God’s Kingdom.
Answered by Fr.Stephen F. Torraco on 12-18-2002