This is a list, in chronological order, of present and past offences to which the Catholic Church has attached the penalty of excommunication; the list is not exhaustive. In most cases these were "automatic excommunications", wherein the violator who knowingly breaks the rule is considered automatically excommunicated from the Church regardless of whether a bishop (or the pope) has excommunicated them publicly. However, in a few cases, a bishop would need to name the person who violated the rule for them to be excommunicated.
Excommunication is an ecclesiastical penalty or censure placed on a person to encourage them to return to communion with the Church. An excommunicated person cannot receive any of the sacraments or exercise any office within the Church until their excommunication is lifted by a valid authority, usually a bishop. Previously, other penalties could also be attached. In cases where excommunication is reserved to the apostolic see, only the Bishop of Rome (i.e., the pope) has the power to lift the excommunication. Before 1869, the Church distinguished "major" and "minor" excommunications; a major excommunication was often marked by simply writing, "Let them be anathema" in council documents. Only offences from the 1983 Code of Canon Law still have legal effect in the Church.
First Council of Nicaea (325 AD) As a priest or deacon, leaving one's church recklessly and failing to return to one's diocese.
Council of Saragossa (380) Receiving Holy Communion by hand. Reaffirmed at the Synod of Toledo (440). Ceased to be an offense in the Latin Church in 1969.
First Council of Constantinople (381) Following any of the following heresies: Eunomianism and Anomoeansmism (that Christ is of an entirely different nature from the Father) Arianism and Eudoxianism (that Christ was created by and thus distinct from God) Semi-Arianism (that the Son and the Spirit, albeit divine, were created by and thus inferior to the Father) Pneumatomachianism (also called Macedonianism, that the Holy Spirit was created by the Son and not divine, and that the Son was of the same substance but a different essence from the Father) Sabellianism (also called monarchianism, that the Father and the Son are the same person) Marcellianisn (also called antinomeanism or libertinism, a supposedly Gnostic belief that only faith and love are necessary to attain salvation, obedience to laws being unnecessary, and that Jesus was only a man, not divine) Photinianism (denying the divinity and pre-existence of Christ) Apollinarism (that Jesus' rational mind was divine, not human)
Council of Ephesus (431) Seeking to upset the decisions of the council of Ephesus. Failing to confess that Jesus is God and Mary is the Mother of God, or that the Word from God the Father has become flesh in Jesus Christ and is God and man in one flesh. Dividing the hypostatic union of Christ, claiming that the two aspects (divine and human) are not united. Claiming that some aspects of Jesus belong to his human part and others to his divine part, rather than belonging to both together. Claiming that Jesus was a God-bearing man and not God in truth. Claiming that the Word from God was the master of Christ and not the same person. Claiming that Jesus as a man was activated by the Word of God and clothed with the glory of God, as though it was separate from him. Claiming that Jesus ought to be worshipped with the Divine Word. Claiming that Jesus' miracles and exorcism were done by the Holy Spirit as an alien power working through him, and not by Jesus' own spirit. Claiming that Jesus became our High Priest, but the Word of God did not become our High Priest, or that Jesus' sacrifice was for himself also. Claiming that the body of Christ is not the Word of God and is not life-giving. Failing to confess that the Word of God became flesh, suffered, died and was resurrected. As a layperson, composing a new creed, different from the Nicene Creed, for the benefit of converting people. As a layperson, following the teachings of Nestorius or Charisius regarding the nature of Christ. As a layperson in the region of Pamphylia, failing to sign the anathema against the Euchites.
Council of Chalcedon (451) Founding a monastery without the approval of the local diocese's bishop; as a monk, failing to obey the local bishop's authority; as a monastery, accepting a slave as a monk without receiving permission from the slave's master. Running a monasteries, martyr's shrine or almshouse without obeying the local bishop's authority. Marrying as a monk or nun. As a bishop, receiving a priest into one's diocese who belongs to another diocese. The priest is also excommunicated in this scenario. Claiming Christ had two natures before the union but a single one after the union. Attempting to produce another creed. Assisting in a simoniacal ordination (i.e., buying the sacrament of holy orders). Priests or religious who go into military service or politics. Carrying off girls under the pretext of cohabitation or assist in such.
Second Council of Constantinople (553) Contradicting the doctrine of hypostatic union defined by the council, including the pre-existence of Christ and his incarnation as a man born of a woman. Specific anathemas were pronounced against Theodore of Mopsuestia, Theodoret, the letter from Ibas to Mari the Persian, and Nestorians. This anathema is made in a very verbose manner, condemning specific beliefs and writings. Denying the perpetual virginity of Mary, or her status as the mother of God. (The former offence is defined in passing, by describing her as "ever-virgin".) Failing to anathematize Arius, Eunomius, Macedonius, Apollinarius Nestorius, Eutyches and Origen, their works, and those anathematized by the previous four synods.
Third Council of Constantinople (680–681) Any religious or laity who attempt to produce another faith, to make or teach or support a new creed, or who use new definitions or novelties or terminology that somehow cancels what has been defined by the council.
Second Council of Nicaea (787) Following any of the heretics mentioned at the council in rejecting church tradition, devising innovations, spurning the things trusted to the church, fabricating evil prejudices against the church's tradition, or secularizing a sacred object or holy monastery. Being in communion with a bishop who acquires his diocese through the help of secular rulers. Preventing the required canonical gatherings of bishops from taking place. Hiding writings composed against the venerable icons. Seizing certain houses belonging to the church referred to in the council and failing to return them. Following the teachings of Arius, Nestorius, Severus of Antioch, Peter the Fuller, Sergius I of Constantinople, Pyrrhus of Constantinople, Pope Honorius I, Cyrus of Alexandria, or Macarius I of Antioch. Condemning the artistic representation of Christ in his humanity. Rejecting representation in art of evangelical scenes. Failing to salute such representations as standing for the Lord and his saints. Rejecting any written or unwritten tradition of the church. Assisting in a simoniacal purchase of ordination.
Fourth Council of Constantinople (869–870) Disobeying the decrees of several popes named by the council. As a lay person, inviting a person excommunicated by the council to paint sacred images or to teach. As a lay person, failing to observe the council's decrees concerning the voiding of contracts made by Photius. Mocking holy things in the manner described by the council or allowing such mockery to take place of things proper to priests. Emperors and others in power were spared if they repented quickly. Others were excommunicated for three years. As a metropolitan bishop, refusing to come to one's patriarch when summoned unless delayed by pagan invasion or genuine illness, or falsely pretending to have no knowledge of the summoning or hiding. As an archbishop or metropolitan, visiting another diocese under the pretext of an official visitation and greedily consuming what belongs to the other diocese. As a bishop, granting the property of a diocese other than one's own as a gift to someone or who installs priests in another diocese. Rejecting the council's directive that a metropolitan can only be judged by a patriarch and not by another metropolitan. Following the teachings of Arius. Claiming that the Divine Word came about and existed by fantasy and supposition. Rejecting the council's condemnation of Photius or supporting him. Rejecting the veneration of icons of Jesus Christ, the Virgin Mary, the angels or saints. Falsifying the word of truth, going through the motions of having false vicars or composing books full of deceptions, explaining them in "favour of his own designs". Believing that the human being has two souls, rather than one. Buying (or acquiring) property belonging to the church, when the bishop selling or giving this property did not have the right to sell or give it, and failing to return this property after buying or acquiring it. As a secular person, removing goods or privileges from the church by force. As a secular ruler, attempting to use force to expel the pope or a patriarch. As a secular ruler or lay person, attempting to act against the proper legal process in a canonical election for a bishop.
First Lateran Council (1123) Carrying off or violating the family or property of crusaders while they are on crusade. As laity, taking offerings from the altars or crosses from any church. Violating a truce and failing to listen to a bishop's admonition to make reparation when the admonition is given three times. Taking part in the military conquest of Benevento from the pope. Harming a church or a person who works in it.
Sicut Judaeis
Violating the bull's rules concerning the protection of Jews, including forcibly converting them.
Second Lateran Council (1139) Violently attacking a cleric or monk (excommunication reserved to the apostolic see). Posing as a nun and receiving guests and secular persons in violation of good morals, unless actually following the rule of Benedict, Basil or Augustine. As a canon of the episcopal see, preventing new elections of bishops from taking place in vacant dioceses. Fighting against Christians as a crossbowman or archer. Illicitly seizing the goods of a deceased bishop. As a lay person, being in possession of a church and failing to restore it to a bishop. Ignoring warnings of a bishop three times to follow a Christian truce. Laying hands on someone who flees to a church or cemetery. Engaging in arson or assisting an arsonist.
Third Lateran Council (1179)
As a layperson, appointing or dismissing a cleric from a church, or seizing, taxing or distributing church property according to one's own will (see Investiture controversy). Imposing an unjust burden on a church or seizing the goods of a church. Sharing a household with a Jew or Muslim. Accepting the testimony of a Jewish witness over the testimony of a Christian witness in a legal case. Supporting, receiving or trading with a Cathar. Claiming to be Pope, or supporting such a claimant, after an election which fails to reach the required two-thirds majority. This was a reaction to the recent antipopes Victor IV, Paschal III and Callixtus III. Acting against the council's decree regarding the return of property taken by schismatics. As a layperson, transferring one's tithe to another layperson. As a layperson, engaging in the "unnatural vice" for which the wrath of God came upon Sodom and Gomorrah. This is a euphemism for sex between men. Ignoring the warnings of a bishop three times to follow a Christian truce.