How do Christians make Sunday "the Lord's day"?
A Catholic Christian attends Holy Mass on Sunday or on the vigil of Sunday. On that day he refrains from all work that would prevent him from worshipping God or disturb the festive, joyful, restful, and restorative character of the day.
Since Sunday is an Easter celebration that occurs each week, Christians from the earliest times have gathered together on that day to celebrate and thank their Redeemer and to reunite themselves with him and with others who are redeemed. So it is a central duty of every conscientious Catholic Christian to "keep holy" Sunday and the other holy days of the Church. One is exempted from it only by urgent family duties and important responsibilities in society. Because participation in the Sunday Eucharist is fundamental for a Christian life, the Church explicitly declares that it is a serious sin to stay away from Sunday Mass without good reason.
Why is it important for the State to preserve Sunday?
Sunday is a genuine service to the good of society, because it is a sign of opposition to the total absorption of man by the working world.
Therefore in lands that have a Christian character, Christians not only demand the governmental preservation of Sunday, they also do not ask others to do work that they themselves do not want to do on Sunday. Everyone in creation should take part in this "breather". (YOUCAT questions 365-366)
Dig Deeper: CCC section (2177-2186) and other references here.
Part 3: Life in Christ (1691 - 2557)
Section 2: The Ten Commandments (2052 - 2557)
Chapter 1: You Shall Love the Lord Your God with All Your Heart, and with All Your Soul, and with All Your Mind (2083 - 2195)
Article 3: The Third Commandment (2168 - 2195)
Remember the sabbath day, to keep it holy. Six days you shall labor, and do all your work; but the seventh day is a sabbath to the Lord your God; in it you shall not do any work.90
The sabbath was made for man, not man for the sabbath; so the Son of Man is lord even of the sabbath.91 ⇡
II. THE LORD'S DAY ⇡
This is the day which the LORD has made; let us rejoice and be glad in it.103 ⇡
The Sunday Eucharist ⇡
The Sunday celebration of the Lord's Day and his Eucharist is at the heart of the Church's life. "Sunday is the day on which the paschal mystery is celebrated in light of the apostolic tradition and is to be observed as the foremost holy day of obligation in the universal Church."110 "Also to be observed are the day of the Nativity of Our Lord Jesus Christ, the Epiphany, the Ascension of Christ, the feast of the Body and Blood of Christi, the feast of Mary the Mother of God, her Immaculate Conception, her Assumption, the feast of Saint Joseph, the feast of the Apostles Saints Peter and Paul, and the feast of All Saints."111
90.
Ex 20:8-10; cf. Deut 5:12-15.
91.
103.
110.
CIC, can. 1246 § 1.
111.
CIC, can. 1246 § 2: "The conference of bishops can abolish certain holy days of obligation or transfer them to a Sunday with prior approval of the Apostolic See."
This practice of the Christian assembly dates from the beginnings of the apostolic age.112 The Letter to the Hebrews reminds the faithful "not to neglect to meet together, as is the habit of some, but to encourage one another."113 Tradition preserves the memory of an ever-timely exhortation: Come to Church early, approach the Lord, and confess your sins, repent in prayer. ... Be present at the sacred and divine liturgy, conclude its prayer and do not leave before the dismissal. ... We have often said: "This day is given to you for prayer and rest. This is the day that the Lord has made, let us rejoice and be glad in it."114
112.
Cf. Acts 2:42-46; 1 Cor 11:17.
113.
114.
Sermo de die dominica 2 et 6:PG 86/1,416C and 421C.
"A parish is a definite community of the Christian faithful established on a stable basis within a particular church; the pastoral care of the parish is entrusted to a pastor as its own shepherd under the authority of the diocesan bishop."115 It is the place where all the faithful can be gathered together for the Sunday celebration of the Eucharist. The parish initiates the Christian people into the ordinary expression of the liturgical life: it gathers them together in this celebration; it teaches Christ's saving doctrine; it practices the charity of the Lord in good works and brotherly love: You cannot pray at home as at church, where there is a great multitude, where exclamations are cried out to God as from one great heart, and where there is something more: the union of minds, the accord of souls, the bond of charity, the prayers of the priests.116
115.
CIC, can. 515 § 1.
116.
St. John Chrysostom, De incomprehensibili 3,6:PG 48,725.
The Sunday obligation ⇡
The precept of the Church specifies the law of the Lord more precisely: "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass."117 "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."118
117.
CIC, can. 1247.
118.
CIC, can. 1248 § 1.
The Sunday Eucharist is the foundation and confirmation of all Christian practice. For this reason the faithful are obliged to participate in the Eucharist on days of obligation, unless excused for a serious reason (for example, illness, the care of infants) or dispensed by their own pastor.119 Those who deliberately fail in this obligation commit a grave sin.
119.
Cf. CIC, can. 1245.
Participation in the communal celebration of the Sunday Eucharist is a testimony of belonging and of being faithful to Christ and to his Church. The faithful give witness by this to their communion in faith and charity. Together they testify to God's holiness and their hope of salvation. They strengthen one another under the guidance of the Holy Spirit.
"If because of lack of a sacred minister or for other grave cause participation in the celebration of the Eucharist is impossible, it is specially recommended that the faithful take part in the Liturgy of the Word if it is celebrated in the parish church or in another sacred place according to the prescriptions of the diocesan bishop, or engage in prayer for an appropriate amount of time personally or in a family or, as occasion offers, in groups of families."120
120.
CIC, can. 1248 § 2.
A day of grace and rest from work ⇡
Just as God "rested on the seventh day from all his work which he had done,"121 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.122
121.
122.
Cf. GS 67 § 3.
On Sundays and other holy days of obligation, the faithful are to refrain from engaging in work or activities that hinder the worship owed to God, the joy proper to the Lord's Day, the performance of the works of mercy, and the appropriate relaxation of mind and body.123 Family needs or important social service can legitimately excuse from the obligation of Sunday rest. The faithful should see to it that legitimate excuses do not lead to habits prejudicial to religion, family life, and health. The charity of truth seeks holy leisure — the necessity of charity accepts just work.124
123.
Cf. CIC, can. 120.
124.
St. Augustine, De civ. Dei 19,19:PL 41,647.
Those Christians who have leisure should be mindful of their brethren who have the same needs and the same rights, yet cannot rest from work because of poverty and misery. Sunday is traditionally consecrated by Christian piety to good works and humble service of the sick, the infirm, and the elderly. Christians will also sanctify Sunday by devoting time and care to their families and relatives, often difficult to do on other days of the week. Sunday is a time for reflection, silence, cultivation of the mind, and meditation which furthers the growth of the Christian interior life.