Catechism of the Catholic Church

2177 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

2178 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

2179 "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