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.
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”.
The Christian Sunday has three essential elements: (1) It recalls the creation of the world and communicates the festive splendor of God’s goodness to the passage of time. (2) It recalls the “eighth day of creation”, when the world was made new in Christ (thus a prayer from the Easter Vigil says: “You have wonderfully created man and even more wonderfully restored him.”). (3) It includes the theme of rest, not just to sanctify the interruption of work, but to point even now toward man’s eternal rest in God.