While it is the first day of the week, Sunday is also called the “eighth day”—a day signifying eternity. Sunday fulfills and completes the Sabbath because it anticipates our eternal rest in God. The Sabbath remembered the first creation. Sunday recalls the new creation in Christ and the Spirit.
The heart of Sunday is the celebration of the Holy Eucharist. The practice of celebrating the Eucharist on Sunday dates from the earliest times. For example, St. Justin Martyr (AD 100-165) wrote as follows: “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” (I Apol. 67: cf. PG 6, 429 and 432; cf. CCC, no. 2174). By their Sunday celebration of the Eucharist, the Catholic faithful fulfill both the Third Commandment to “keep holy the Lord’s day” and the words of Jesus to his disciples at the Last Supper: “Do this in memory of me” (Lk 22:19).
The Third Commandment has been concretized for Catholics by one of the Precepts of the Church.
Because the faithful are obliged to attend Mass unless there is a grave impediment, pastors have the corresponding duty to offer everyone the real possibility of fulfilling the precept. . . . Yet more than a precept, the observance should be seen as a need rising from the depths of Christian life. It is crucially important that all the faithful should be convinced that they cannot live their faith or share fully in the life of the Christian community unless they take part regularly in the Sunday Eucharistic assembly. (DD, nos. 49, 81)
For a Catholic, the Sunday Eucharist must be the most important religious exercise of the week. In it, we offer our lives in sacrifice with Jesus to the Father, thereby participating directly in the great mysteries of our faith.
The Catholic parish, shepherded by the priest under the authority of the diocesan bishop, is the ordinary setting for Sunday worship and is central to the preparation for and celebration of all the Sacraments.
While Sunday is the time for worship, it is also an occasion for rest and relaxation. We should make time to be with one another in meals, conversation and activities that deepen family life. “Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day. Traditional activities (sports, restaurants, etc.), and social necessities (public services, etc.), require some people to work on Sundays, but everyone should still take care to set aside sufficient time for leisure” (CCC, no. 2187; cf. no. 2186). The Eucharistic celebration does not stop at the church door. Those who participate at Mass carry their joy, faith, and concern for others from the Mass into the rest of the day, and indeed into the week that follows.
You can read more from the United States Catholic Catechism for Adults, order your own copy, or read questions about it at the United States Conference of Catholic Bishops website.
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