The Roman Catholic church, the largest of the Christian churches, although present in all parts of the world, is identified as Roman because of its historical roots in Rome and because of the importance it attaches to the worldwide ministry of the bishop of Rome, the pope. Several Eastern Rite Churches, whose roots are in regional churches of the Eastern Mediterranean, are in full communion with the Roman Catholic church.

A growing estrangement between the Catholic church in the West and the Orthodox church of the East in the first millennium led to a break between them in the 11th century, and the two regions diverged in matters of theology, liturgy, and disciplinary practices. Within Western Christianity beginning with the 16th - century Reformation, the Roman Catholic church came to be identified by its differences with the Protestant churches.

The public worship of the Roman Catholic church is its liturgy, principally the Eucharist, which is also called the Mass. After the recitation of prayers and readings from the Bible, the presiding priest invites the faithful to receive communion, understood as sharing in the sacramental presence of Christ. At the Sunday liturgy the priest preaches a sermon or homily, applying the day's biblical texts to the present lives of believers. The church observes a liturgical calendar similar to that of other Christians, following a cycle of Advent, Christmas, Epiphany, Lent, Easter, and Pentecost. It also follows a distinctive cycle of commemoration of the saints. The worship of the church is expressed as well in rites of baptism, confirmation, weddings, ordinations, penitential rites, burial rites or funerals, and the singing of the Divine Office. A distinguishing mark of Catholic worship is prayer for the