Pope

=== Nicaea to East–West Schism (325–1054) ===
{{See also|Papacy in late antiquity}}
The [[Edict of Milan]] in 313 granted freedom to all religions in the Roman Empire,<ref>Davidson, Ivor (2005). ''The Birth of the Church''. Monarch. p. 341. {{ISBN|1-85424-658-5}}.</ref> beginning the [[Peace of the Church]]. In 325, the [[First Council of Nicaea]] condemned [[Arianism]], declaring [[trinitarianism]] dogmatic, and in its sixth canon recognized the special role of the Sees of Rome, Alexandria, and Antioch.<ref>"Let the ancient customs in Egypt, Libya and Pentapolis prevail, that the Bishop of Alexandria has jurisdiction over them all, since a similar arrangement is the custom for the Bishop of Rome. Likewise let the churches in Antioch and the other provinces retain their privileges" ([http://www.fourthcentury.com/index.php/nicaea-325-canons Canons of the Council of Nicaea] {{webarchive|url=https://web.archive.org/web/20120215233640/http://www.fourthcentury.com/index.php/nicaea-325-canons |date=15 February 2012 }}).</ref> Great defenders of Trinitarian faith included the popes, especially [[Pope Liberius|Liberius]], who was exiled to [[Veria|Berea]] by [[Constantius II]] for his Trinitarian faith,<ref>{{cathEncy|wstitle=Pope Liberius|author=Chapman, Henry Palmer}}</ref> [[Damasus I]], and several other bishops.<ref name="Alves J.">Alves J. ''Os Santos de Cada Dia'' (10 edição). Editora Paulinas. pp. 296, 696, 736. {{ISBN|978-85-356-0648-5}}.</ref>

In 380, the [[Edict of Thessalonica]] declared [[Nicene Christianity]] to be the state religion of the empire, with the name "Catholic Christians" reserved for those who accepted that faith.<ref>[http://www.fordham.edu/halsall/source/theodcodeXVI.html Theodosian Code] {{Webarchive|url=https://web.archive.org/web/20070227120555/http://www.fordham.edu/halsall/source/theodcodeXVI.html |date=27 February 2007 }} XVI.i.2, Medieval Sourcebook: Banning of Other Religions by Paul Halsall, June 1997, Fordham University, retrieved 4 September 2007</ref><ref>Wilken, Robert (2004). "Christianity". in Hitchcock, Susan Tyler; Esposito, John. Geography of Religion. National Geographic Society. p. 286. {{ISBN|0-7922-7317-6}}.</ref> While the civil power in the [[Eastern Roman Empire]] controlled the church, and the [[patriarch of Constantinople]], the capital, wielded much power,<ref name="GAETA">Gaeta, Franco; Villani, Pasquale. ''Corso di Storia, per le scuole medie superiori''. Milão. Editora Principato. 1986.</ref> in the [[Western Roman Empire]], the bishops of Rome were able to consolidate the influence and power they already possessed.<ref name="GAETA" /> After the [[fall of the Western Roman Empire]], [[barbarian]] tribes were converted to Arian Christianity or Nicene Christianity;<ref name="Le Goff">Le Goff, Jacques (2000). ''Medieval Civilization''. Barnes & Noble. pp. 14, 21. {{ISBN|0-631-17566-0}}.</ref> [[Clovis I]], king of the [[Franks]], was the first important barbarian ruler to convert to the mainstream church rather than Arianism, allying himself with the papacy. Other tribes, such as the [[Visigoths]], later abandoned Arianism in favour of the established church.<ref name="Le Goff" />

==== Middle Ages ====
[[File:Gregorythegreat.jpg|thumb|upright|Gregory the Great ({{circa|540–604}}), in a painting by [[Carlo Saraceni]], {{circa|1610}}, Rome.]]
After the fall of the Western Roman Empire, the pope served as a source of authority and continuity. [[Pope Gregory I]] ({{circa|540–604}}) administered the church with strict reform. From an ancient senatorial family, Gregory worked with the stern judgement and discipline typical of ancient Roman rule. Theologically, he represents the shift from the classical to the medieval outlook; his popular writings are full of dramatic [[miracle]]s, potent [[relic]]s, [[demon]]s, [[angel]]s, ghosts, and the [[Eschatology|approaching end of the world]].{{sfn|Durant|1950|pp=517–551}}

Gregory's successors were largely dominated by the [[exarch of Ravenna]], the [[List of Byzantine emperors|Byzantine emperor]]'s representative in the [[Italian Peninsula]]. These humiliations, the weakening of the [[Byzantine Empire]] in the face of the [[Early Muslim conquests|Muslim conquests]], and the inability of the emperor to protect the papal estates against the [[Lombards]], made [[Pope Stephen II]] turn from Emperor [[Constantine V]]. He appealed to the Franks to protect his lands. [[Pepin the Short]] subdued the Lombards and donated Italian land to the papacy. When [[Pope Leo III]] crowned [[Charlemagne]] (800) as emperor, he established the precedent that, in Western Europe, no man would be emperor without being crowned by a pope.{{sfn|Durant|1950|pp=517–551}}

The low point of the papacy was 867–1049.{{sfn|Durant|1950|loc=chpt. 4}} This period includes the {{lang|la|[[Saeculum obscurum]]}}, the [[Crescentii]] era, and the [[Tusculan Papacy]]. The papacy came under the control of vying political factions. Popes were variously imprisoned, starved, killed, and deposed by force. The family of a certain papal official{{who|date=January 2024}} made and unmade popes for fifty years. The official's great-grandson, [[Pope John XII]], held orgies of debauchery in the [[Lateran Palace]]. Emperor [[Otto I]] had John accused in an ecclesiastical court, which deposed him and elected a layman as [[Pope Leo VIII]]. John mutilated the Imperial representatives in Rome and had himself reinstated as pope. [[History of the papacy (1048–1257)|Conflict between the Emperor and the papacy]] continued, and eventually dukes in league with the emperor were buying bishops and popes almost openly.{{sfn|Durant|1950|loc=chapter 4}}

In 1049, [[Leo IX]] travelled to the major cities of Europe to deal with the church's moral problems firsthand, notably [[simony]] and [[clerical marriage]] and [[concubinage]]. With his long journey, he restored the prestige of the papacy in Northern Europe.{{sfn|Durant|1950|loc=chapter 4}}

From the 7th century it became common for European monarchies and nobility to found churches and perform [[investiture]] or deposition of clergy in their states and fiefdoms, their personal interests causing corruption among the clergy.<ref name="H.G.B">''História Global Brasil e Geral''. pp. 101, 130, 149, 151, 159. Volume one. Gilberto Cotrim. {{ISBN|978-85-02-05256-7}}</ref><ref name="Missão Jovem">[http://www.pime.org.br/missaojovem/mjhistdaigrejareforma.htm Movimentos  de Rennovação  e Reforma] {{webarchive|url=https://web.archive.org/web/20120116233149/http://www.pime.org.br/missaojovem/mjhistdaigrejareforma.htm |date=16 January 2012 }}. 1 October 2009.</ref> This practice had become common because often the prelates and secular rulers were also participants in public life.<ref>{{cite web |url=http://www.portalsaofrancisco.com.br/alfa/feudalismo/feudalismo.php |title=Feudalismo |publisher=Portalsaofrancisco.com.br |access-date=18 February 2013 |archive-date=4 February 2013 |archive-url=https://web.archive.org/web/20130204210934/http://www.portalsaofrancisco.com.br/alfa/feudalismo/feudalismo.php |url-status=live }}</ref>

To combat this and other practices that had been seen as corrupting the Church between the years 900 and 1050, centres emerged promoting ecclesiastical reform, the most important being the [[Abbey of Cluny]], which spread its ideals throughout Europe.<ref name="Missão Jovem" /> This reform movement gained strength with the election of [[Pope Gregory VII]] in 1073, who adopted a series of measures in the movement known as the [[Gregorian Reform]], in order to fight strongly against simony and the abuse of civil power and try to restore ecclesiastical discipline, including [[clerical celibacy]].<ref name="Alves J." />

This conflict between popes and secular autocratic rulers such as the Holy Roman Emperor [[Henry IV, Holy Roman Emperor|Henry IV]] and King [[Henry I of England]], known as the [[Investiture controversy]], was only resolved in 1122, by the [[Concordat of Worms]], in which [[Pope Callixtus II]] decreed that clerics were to be invested by clerical leaders, and temporal rulers by lay investiture.<ref name="H.G.B" /> Soon after, [[Pope Alexander III]] began reforms that would lead to the establishment of [[canon law]].{{sfn|Durant|1950|pp=517–551}}

Since the beginning of the 7th century, [[Early Muslim conquests|Islamic conquests]] had succeeded in controlling much of the southern [[Mediterranean]], and represented a threat to Christianity.<ref>Vidmar, John (2005). ''The Catholic Church Through the Ages''. Paulist Press. p. 94. {{ISBN|0-8091-4234-1}}.</ref> In 1095, the Byzantine emperor, [[Alexios I Komnenos]], asked for military aid from [[Pope Urban II]] in the ongoing [[Byzantine–Seljuq wars]].<ref>Riley-Smith, Jonathan (1997). ''The First Crusaders''. Cambridge University Press. p. 6. {{ISBN|978-0-511-00308-0}}.</ref> Urban, at the [[council of Clermont]], called the [[First Crusade]] to assist the Byzantine Empire to regain the old Christian territories, especially Jerusalem.{{sfn|Bokenkotter|2004|pp=140–141, 192}}