天主教；罗马公教(Roman Catholicism)
世界上最大的基督教单一教会，信徒人数接近十亿，或者说占世界人口总数的18%。天主教对西方文明的发展有过深厚的影响，并将基督教传播到世界的许多地方。天主教认为本教是耶稣基督的唯一合法继承者，从使徒圣彼得开始不间断地延续到现在。教宗是神启的一贯正确的解释者。教会组织有严格的等级。由教宗指定并统领约150名枢机主教。教会500名大主教中的每一个都是一个大主教辖区的首领。这些大主教辖区又分成约1,800个主教辖区，每个辖区有一名主教为首。在主教辖区内有许多堂区，每个堂区有一个教堂和一个神父。只有男子可以担任神职，女子想从事圣职可以当修女，修女们也可组织修会和建立女修道院。礼拜的基本形式是弥撒，是庆祝圣餐的圣事。从神学上说，天主教与新教的不同之处在於它们对启示的来源和恩典的手段的理解不同。东正教认为经籍和教会传统都是基督教信仰基础和教会政策的展示。天主教确立了七种圣事（洗礼、赎罪、圣餐、婚礼、圣职授任、坚振礼和涂油於病人）；另外还有其他的奉献行为加入此丰富的圣事生活中，主要是圣餐仪式和向圣人奉献。第二次梵谛冈会议（1962～1965）放宽了教会在许多方面的限制，但妇女在教会中的角色地位、神职人员的禁欲、教会反对离婚、人工避孕以及堕胎等问题至今尚未解决。
English version：
Roman Catholicism
Largest single Christian denomination in the world, with nearly one billion members, or 18% of the world's population. The Roman Catholic church has had a profound effect on the development of Western civilization and has been responsible for introducing Christianity in many parts of the world. It regards itself as the only legitimate inheritor of the ministry of Jesus, by virtue of an unbroken succession of leaders beginning with St. Peter the Apostle and continuing to the present day. It holds that the pope is the infallible interpreter of divine revelation. Church organization is strictly hierarchical. The pope appoints and presides over about 150 cardinals. Each of the church's 500 archbishops is the head of an archdiocese. These in turn are divided into about 1,800 dioceses, each headed by a bishop. Within dioceses are parishes, each served by a church and a priest. Only men can enter the priesthood, but women who wish to enter holy orders can become nuns, who are organized into orders and convents. The basic form of worship is the mass, which celebrates the sacrament of the Eucharist. Theologically, Roman Catholicism differs from Protestantism with regard to its understanding of the sources of revelation and the channels of grace. With Eastern Orthodoxy it asserts that both scripture and church tradition are revelatory of the basis of Christian belief and church polity. It sets the number of sacraments at seven (baptism, penance, Eucharist, matrimony, ordination, confirmation, and anointing of the sick); its rich sacramental life is supplemented by other devotions, chiefly Eucharistic services and devotions to the saints. The Second Vatican Council (1962-65) liberalized many aspects of the church; the role of women in the church, clerical celibacy, church opposition to divorce, contraception by artificial means, and abortion remain contentious issues.