“If pagans call it the ‘day of the sun,’ we willingly agree, for today the light of the world is raised, today is revealed the sun of justice with healing in his rays.” – St. Jerome (347-419).
According to the Catechism of the Catholic Church, Sunday, the “Lord’s Day” is the most important day of the week. The Catechism says this about Sunday:
“Observe the Sabbath day, to keep it holy” (Duet 5:12). “The seventh day is a Sabbath of solemn rest, holy to the Lord” (Ex 31:15). # 2189
The Sabbath, which represented the completion of the first creation, has been replaced by Sunday which recalls the new creation inaugurated by the Resurrection of Christ. #2190
The Church celebrates the day of Christ’s Resurrection on the “eighth day,” Sunday, which is rightly called the Lord’s Day (cf. SC 106). #2191
“Sunday … is to be observed as the foremost holy day of obligation in the universal Church” (CIC, can. 1246). On Sundays and other holy days of obligation the faithful are bound to participate in the Mass” (CIC, can.1247). #2192
“On Sundays and other holy days of obligation the faithful are bound … to abstain from those labors and business concerns which impede the worship to be rendered to God, the joy which is proper to the Lord’s Day, or the proper relaxation of mind and body” (CIC, can. 1247). #2193
The institution of Sunday helps all “to be allowed sufficient rest and leisure to cultivate their familial, cultural, social and religious lives” (GS 67). #2194
Every Christian should avoid making unnecessary demands on others that would hinder them from observing the Lord’s Day. #2195