The third commandment of the Decalogue is to keep holy the Sabbath. It calls us to honour God also with our worship on Sundays and other feast days.
Sunday or the Lord’s Day
The Bible recounts the work of creation in six “days.” At the end “God saw everything that he had made, and behold, it was very good . . . So God blessed the seventh day and hallowed it, because on it God rested from all his work which he had done in creation” (Gen 1:31; 2:3)
In the Old Testament, God decreed that the seventh day of the week should be holy, a day set off and distinct from the others. Man, who is called to participate in the creative power of God, perfecting the world through his work, is also to cease working on the seventh day in order to dedicate it to divine worship and to rest. Thus the Lord seeks to protect in the human heart the true order of the life of God’s children, so that the dynamics and requirements of work and other daily realities are integrated in practice with the authentic priorities and the true meaning of creation.
The primary content of this precept is not, therefore, merely the interruption of work, but to remember and celebrate – which is to live as truly present, by the power of the Holy Spirit – the wonders worked by God, to thank and praise Him for them. Thus the command to rest reveals its full meaning: we are to share deeply in God’s own “rest” and experience the same joy the Creator experienced after creation, on seeing that all He had made “was very good.”
“And then begins the day of rest, which is God’s joy in what he has created. It is the day of contemplation and blessing. What then is rest according to this commandment? It is the time of contemplation; it is the time of praise, not of escape. It is the time to look at reality and say: how beautiful life is! The Decalogue opposes – to rest as an escape from reality – rest as a blessing of reality” (Pope Francis, General Audience, 5 September 2018).
Before the coming of Christ, the seventh day was the Sabbath. In the New Testament it is Sunday, Dies Domini, the day of the Lord, because it is the day of the Lord’s Resurrection. The Sabbath represented the end of creation; Sunday represents the beginning of the “new creation,” which took place with Christ’s resurrection (cf. Catechism 2174).
Participation in Holy Mass on Sunday
Since the Sacrifice of the Eucharist is the source and summit of the life of the Church, and therefore also of every member of the faithful, Sunday is sanctified primarily by participating in Holy Mass. “For us Christians, the centre of the Lord’s Day, Sunday, is the Eucharist, which means ‘thanksgiving.’ It is the day to say to God: thank you Lord for life, for your mercy, for all your gifts” (Pope Francis, General Audience, 5 September 2018).
The Church expressed the third commandment of the Decalogue concretely in the following decree: “On Sundays and other holy days of obligation the faithful are bound to participate in the Mass” (CIC, can. 1247; Catechism 2180). Outside of Sundays, the main days of obligation are: “Christmas, the Epiphany, the Ascension, the Body and Blood of Christ, Mary the Mother of God, her Immaculate Conception, her Assumption, Saint Joseph, the Apostles Saints Peter and Paul, and lastly All Saints” (CIC, can. 1246; Catechism 2177).
“The precept of participating in the Mass is satisfied by assistance at a Mass which is celebrated anywhere in a Catholic rite either on the holy day or on the evening of the preceding day (CIC, can. 1248)” (Catechism, 2180). “Evening” is to be understood here as the canonical hour of Vespers (approximately between 4 and 6 pm), or later.
The precept binds the faithful, “unless excused for a serious reason (for example, illness, the care of infants) or dispensed by their own pastor (cf. CIC, can. 1245). Those who deliberately fail in this obligation commit a grave sin” (Catechism, 2181).
It is also worth considering that when the Church urges these minimums of participation in the Eucharist, thus concretising the principal way of “sanctifying feasts,” she acts especially as a mother who is concerned that her children should not lack the essential nourishment they need to live as children of God. Hence, more than a duty, the baptised have the need and the right to participate in the celebration of the Eucharist. In the Acts of the Apostles (2:42), we read that the first Christians “devoted themselves to the apostles’ teaching and fellowship, to the breaking of bread and the prayers.” The Church’s rule seeks precisely to protect and foster this original vitality of the Christian vocation.
Sunday, a day of rest
“Just as God ‘rested on the seventh day from all his work which he had done’ (Gen 2:2), human life has a rhythm of work and rest. The institution of the Lord’s Day helps everyone enjoy adequate rest and leisure to cultivate their familial, cultural, social, and religious lives” (Catechism 2184). On Sundays and other holy days of obligation, the faithful are to refrain “from work and activities that hinder the worship owed to God, the joy proper to the Lord’s Day, and the appropriate relaxation of mind and body” (CIC, can. 1247). This constitutes a serious obligation, as is that of sanctifying feast days. However, a more important duty of justice or charity can excuse one from the obligation of Sunday rest. Nevertheless, the Church reminds us that “every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day” (Catechism, 2187).
In some countries today, there is a widespread mentality that considers religion to be a private matter that should not have public and social manifestations. On the contrary, Christian doctrine teaches that all men and women should be “free to profess their religion in public and in private.” Indeed, the natural moral law, inscribed in man’s heart, prescribes “giving God external, visible, public worship” (Cf. Catechism, 2176).
Certainly, worshiping God is first of all a private act, but people need to be able to manifest it exteriorly because the human spirit “needs to use material things as signs by means of which it is prompted to carry out the spiritual acts that unite it to God.”
Moreover, people need to be free to profess religion not only exteriorly, but also socially, that is, with others, because “the social nature of man itself requires that he should give external expression to his internal acts of religion.” “Injury therefore is done to the human person and to the very order established by God for human life, if the free exercise of religion is denied in society, provided just public order is observed . . . Government therefore ought indeed to take account of the religious life of the citizenry and show it favor, since the function of government is to make provision for the common welfare.”
There is a social and civil right to freedom in religious matters. Society and the government cannot hinder anyone from acting in this area in accord with the dictates of their conscience, whether in private or in public, while respecting just limits derived from the requirements of the common good, such as public order and public morality (cf.Catechism, 2109).
Therefore, “in respecting religious liberty and the common good of all, Christians should seek recognition of Sundays and the Church’s holy days as legal holidays. They have to give everyone a public example of prayer, respect, and joy and defend their traditions as a precious contribution to the spiritual life of society” (Catechism, 2188). As Saint Josemaría wrote: “Your task as a Christian citizen is to help see Christ’s love and freedom preside over all aspects of modern life: culture and the economy, work and rest, family life and social relations.”
Each person is obliged in conscience to seek the true religion and to adhere to it. In this search they can receive help from others (indeed, the Christian faithful have the duty to give this help by their example and word), but no one is to be coerced. Adherence to the faith must always be free, as must its practice (cf. Catechism, 2104-2106).
Catechism of the Catholic Church, 2168-2188; John Paul II, Apostolic Letter Dies Domini, 31 May 1998.
Benedict XVI-Joseph Ratzinger, Jesus of Nazareth, vol. 1 (chap. 5, sect. 2).
Saint Josemaría, Homily Getting to know God, in Friends of God, 142-153.
Pope Francis, General Audience, 8 November 2017. This is the beginning of the Pope’s catechesis on the Eucharist.
 Cf. Second Vatican Council, Sacrosanctum Concilium, 10.
 Second Vatican Council, Dignitatis humanae, 15; Catechism, 2137.
 Saint Thomas Aquinas, S. Th., II-II, q. 122, a. 4, c.
 Saint Thomas Aquinas, S. Th., II-II, q. 81, a. 7, c.
 Second Vatican Council, Dignitatis humanae, 3.
 Ibid., 7.
 Saint Josemaría, Furrow, 302.