Hierarchy of the Catholic Church in the context of "Hagia Sophia"

A particular church (Latin: ecclesia particularis) is an ecclesiastical community of followers headed by a bishop (or equivalent), as defined by Catholic canon law and ecclesiology. A liturgical rite, a collection of liturgies descending from shared historic or regional context, depends on the particular church the bishop (or equivalent) belongs to. Thus the term "particular church" refers to an institution, and "liturgical rite" to its ritual practices.

In the canon law of the Catholic Church, excommunication (Lat. ex, "out of", and communio or communicatio, "communion"; literally meaning "exclusion from communion") is a form of censure. In the formal sense of the term, excommunication includes being barred not only from the sacraments but also from the fellowship of Christian baptism. The principal and severest censure, excommunication presupposes guilt; and being the most serious penalty that the Catholic Church can inflict, it supposes a grave offense. The excommunicated person is considered by Catholic ecclesiastical authority as an exile from the Church, for a time at least.

Excommunication is intended to invite the person to change behaviour or attitude, repent, and return to full communion. It is not an "expiatory penalty" designed to make satisfaction for the wrong done, much less a "vindictive penalty" designed solely to punish. Excommunication, which is the gravest penalty of all, is always "medicinal".

Canon law (from Latin ius canonicum) is the system of religious laws and ecclesiastical legal principles made and enforced by the hierarchical authorities of the Catholic Church to regulate its external organization and government and to order and direct the activities of Catholics toward the mission of the Church.

It is the first modern Western legal system and is the oldest continuously functioning legal system in the West, while the unique traditions of Eastern Catholic canon law govern the 23 Eastern Catholic particular churches sui iuris.

The Fourth Council of the Lateran or Lateran IV was convoked by Pope Innocent III in April 1213 and opened at the Lateran Palace in Rome on 11 November 1215. Due to the great length of time between the council's convocation and its meeting, many bishops had the opportunity to attend this council, which is considered by the Catholic Church to be the twelfth ecumenical council.

The council addressed a number of issues, including the sacraments, the role of the laity, the treatment of Jews and heretics, and the organization of the church. The decree mandating annual confession has been called "perhaps the most important legislative act in the history of the church."