Catholic Church

Vatican City, officially the Vatican City State (Italian: Stato della Città del Vaticano; Latin: Status Civitatis Vaticanae), often shortened as the Vatican, is a landlocked sovereign city-state. Ruled by the pope, it is an enclave within Rome and serves as the administrative centre of the Catholic Church. Vatican City is governed by the See of Rome, commonly known as the Holy See, itself a sovereign entity under international law, which maintains its temporal power, governance, diplomacy, and spiritual independence. Vatican is also used as a metonym for the Holy See, which is the central governing body of the Catholic Church and Vatican City, comprising the pope and the Roman Curia. The independent state of Vatican City came into existence in 1929 via the Lateran Treaty between the Holy See and the Kingdom of Italy, which spoke of it as a new creation, not as a vestige of the much larger Papal States (756–1870), which had previously encompassed much of Central Italy.

With an area of 48.99 hectares (121 acres) and a population of about 882 in 2024, it is the smallest sovereign state in the world both by area and by population. It is among the least populated capitals in the world. As governed by the Holy See, Vatican City State is an ecclesiastical or sacerdotal-monarchical state ruled by the pope, who is the bishop of Rome and head of the Catholic Church; the highest state functionaries are all Catholic clergy of various origins. The Holy See dates to early Christianity and is the principal episcopal see of the Catholic Church, which in 2018 had about 1.329 billion baptized Catholics in the world, in the Latin Church and 23 Eastern Catholic Churches. After the Avignon Papacy (1309–1377) the popes have mainly resided at the Apostolic Palace within what is now Vatican City, although at times residing instead in the Quirinal Palace in Rome or elsewhere.

Christianity has been the largest religion in Ireland since the 5th century. After a pagan past of Antiquity, missionaries (most famously including Saint Patrick) converted the Irish tribes to Christianity in quick order. This produced a great number of saints in the Early Middle Ages, as well as a faith interwoven with Irish identity for centuries since − though less so in recent times.

Most Christian churches are organized on an "all-Ireland" basis, including both the Republic of Ireland and Northern Ireland. In the 2022 census, 76.1% of residents in the Republic of Ireland identified as Christians: 69.1% as Catholics, 4.2% as Protestants, 2.1% as Orthodox Christians and 0.7% as other Christians. In the 2021 Northern Irish census, 79.7% of residents identified as Christians: 42.3% as Catholics, 16.6% as Prebysterian, 11.5% as Church of Ireland members, 2.4% as Methodist and 6.9% as other Christians. Orthodoxy has been the fastest growing branch of Christianity in Ireland since 1991.

Christianity is the most widely professed religion in Croatia, representing 87.34% of the total population. A large majority of the Croats declare themselves to be members of the Catholic Church.

Religion in Poland is rapidly declining, although historically it had been one of the most Catholic countries in the world.

Religion in Hungary is varied, with Christianity being the largest religion. In the national census of 2022, 42.5% of the population identified themselves as Christians, of whom 29.2% were adherents of Catholicism (27.5% following the Roman Rite, and 1.7% the Greek Rite), 9.8% of Calvinism, 1.8% of Lutheranism, 0.2% of Eastern Orthodox Christianity, and 1.5% of other Christian denominations. 1.3% of the population identified themselves as adherents of other religions; minorities practising Judaism, Islam, Buddhism, Hinduism, the Baháʼí Faith, Taoism, Hungarian Neopaganism and other Neopaganisms, and New Age, are present in the country. At the same time, 40.1% of the population did not answer, not identifying their beliefs or non-beliefs, while 16.1% identified themselves as not religious.

Religion in Bulgaria has been dominated by Christianity since its adoption as the state religion in 864. The dominant form of the religion is Eastern Orthodox Christianity within the fold of the Bulgarian Orthodox Church. During the Ottoman rule of the Balkans, Islam spread to the territories of Bulgaria, and it remains a significant minority today. The Catholic Church has roots in the country since the Middle Ages, and Protestantism arrived in the 19th century; both of them remain very small minorities. Today, a significant part of the Bulgarians are not religious, or believers who do not identify with any specific religion, and Bulgaria has been the cradle of some new religions, notably the Neo-Theosophical movement of Dunovism.

Christianity in Italy has been historically characterised by the dominance of the Catholic Church since the East–West Schism. However, the country is also home to significant Christian minorities, especially Orthodox Christians, Protestants and Jehovah's Witnesses.

The country's patron saints are Francis of Assisi and Catherine of Siena.

Christianity is a prevalent religion in Denmark; in January 2023, 72.1% of the population of Denmark were members of the Church of Denmark. According to a survey based on a sample 1,114, 25% of Danes believe Jesus is the son of God, and 18% believe he is the saviour of the world. Aside from Lutheranism, there is a small Catholic minority, as well as small Protestant denominations such as the Baptist Union of Denmark and the Reformed Synod of Denmark.

Denmark has Lutheranism as the state religion, as such its culture is heavily influenced by Christianity.

Religion in Slovakia is predominantly Christianity, adhered to by about 68.8% of the population in 2021.

The Catholic Church is the major Christian tradition in the country, followed in 2021 by 59.8% of the population, a majority of whom (55.8%) were of the Latin Church and a minority of whom (4%) were of the Slovak Greek Catholic Church. About 9% of the population were mostly followers of Protestantism, and a minority of Eastern Orthodox Church and other Christian denominations; the major groupings are the Evangelical Church of the Augsburg Confession in Slovakia (5.3%), the Reformed Christian Church in Slovakia (1.6%), the Orthodox Church of the Czech Lands and Slovakia (0.9%), the Jehovah's Witnesses (0.3%), and other smaller Christian denominations (0.9%). In 2021, about 23.8% of the population declared themselves not religious, an increase from 13.4% in 2011. An additional 1.2% of the population were followers of other religions or beliefs; small religious minorities in Slovakia include Buddhism, modern Paganism, Islam, Judaism, Jediism, Hinduism

According to the Lithuanian census of 2021, the predominant religion in Lithuania is Christianity, with the largest confession being that of the Catholic Church (about 74% of the population). There are smaller groups of Orthodox Christians, Evangelical Lutherans, members of Reformed churches, other Protestants, Jews and Muslims as well as people of other religions.