question: why did christianity become so popular in so many countries?
comment: Those religions that command their adherents to proselytize and convert others to their faith, whether by persuasion or coercion (e.g. Christianity, Islam, Buddhism, etcetera) — generically referred to as "Missionary Religions" — are better at spreading across vast regions of the globe than religions that DO NOT command their adherents to convert others (e.g. Judaism, Shinto, etcetera). Christianity and Islam in particular have spread not just through missionary proselytism but also through military conquest and the forced conversion of subjugated nations, Buddhism not as much. Religions that neither proselytize nor conquer can pretty much only grow by adherents having more children. Some religions command followers to proselytize *and* have as many children as possible (e.g. Catholicism and Mormonism).
passages: The early followers of Jesus, including Saints Paul and Peter carried this new theology concerning Jesus throughout the Roman Empire and beyond, sowing the seeds for the development of the Catholic Church, of which Saint Peter is remembered as the first Pope. Catholicism, as we know it, emerged slowly. Christians often faced persecution during these early centuries, particularly for their refusal to join in worshiping the emperors. Nevertheless, carried through the synagogues, merchants and missionaries across the known world, the new internationalist religion quickly grew in size and influence. Its unique appeal was partly the result of its values and ethics.
   Later waves of colonial expansion such as the Scramble for Africa or the struggle for India, by the Netherlands, Britain, France, Germany and Russia led to Christianization of other native populations across the globe such as the Indigenous peoples of the Americas, Filipinos, Indians and Africans led to the expansion of Christianity eclipsing that of the Roman period and making it a truly global religion.
  
  Section::::Colonial era (16th−19th centuries).:United States.
   BULLET::::- 1596 Ukrainian Catholic Church forms when Ukrainian subjects of the king of Poland are reunited with Rome, largest Byzantine Catholic Church
  
  BULLET::::- 1598 Edict of Nantes grants toleration to French Protestants (Huguenots)
  
  BULLET::::- 1600 Giordano Bruno, Dominican priest, burned at the stake
  
  Section::::17th century.
  
  BULLET::::- 1604 Fausto Paolo Sozzini Socinianism
  
  BULLET::::- 1606 Carlo Maderno redesigns St Peter's Basilica into a Latin cross
  
  BULLET::::- 1607 Jamestown, Virginia founded
  
  BULLET::::- 1608 Quebec City founded by Samuel de Champlain
  
  BULLET::::- 1609 Baptist Church founded by John Smyth, due to objections to infant baptism and demands for church-state separation
   BULLET::::- 325 The Kingdom of Aksum (Modern Ethiopia and Eritrea) declares Christianity as the official state religion, becoming the 2nd country to do so
  
  BULLET::::- 325 Church of the Nativity in Bethlehem, ordered built by Constantine
  
  BULLET::::- 326, November 18 Pope Sylvester I consecrates the Basilica of St. Peter built by Constantine the Great over the tomb of the Apostle
  
  BULLET::::- 328-373 Athanasius, bishop of Alexandria, first cite of modern 27 book New Testament canon
  
  BULLET::::- 330 Old Church of the Holy Apostles, dedicated by Constantine
   BULLET::::- 280 – First rural churches emerge in northern Italy; Christianity is no longer exclusively in urban areas
  
  BULLET::::- 287 – Maurice from Egypt is killed at Agauno, Switzerland for refusing to sacrifice to pagan divinities
  
  BULLET::::- 300 – First Christians reported in Greater Khorasan; an estimated 10% of the world's population is now Christian; parts of the Bible are available in 10 different languages
  
  BULLET::::- 304 – Armenia accepts Christianity as state religion
  
  BULLET::::- 306 – The first bishop of Nisibis is ordained
   BULLET::::- 1950 Assumption of Mary decreed by Pope Pius XII
  
  BULLET::::- 1950 Missionaries of Charity founded by Mother Teresa
  
  BULLET::::- 1951 Bishop Fulton Sheen (1919–1979) debuts his television program "Life is Worth Living" on the DuMont Network. His half hour lecture program on Roman Catholic theology remained the number one show on U.S. television for its time slot, winning several Emmys until Sheen ended the program in 1957
   Christianity and Christian ethics played a prominent role in the development of Western civilization, particularly around Europe during late antiquity and the Middle Ages. Despite a decline in adherence in the West, Christianity remains the dominant religion in the region, with about 70% of the population identifying as Christian. Christianity is growing rapidly in Africa and Asia, the world's most populous continents.
  
  Section::::Etymology.
   BULLET::::- 718-1492 Reconquista: Iberian Peninsula retaken by Roman Catholic Visigoth monarchs
  
  BULLET::::- 718 Saint Boniface, archbishop of Mainz; an Englishman, given commission by Pope Gregory II to evangelize the Germans
  
  BULLET::::- 720? Disentis Abbey of Switzerland
  
  BULLET::::- 730-787 : Byzantine Emperor Leo III bans Christian icons; Pope Gregory II excommunicates him
  
  BULLET::::- 731 English Church History written by Bede
  
  BULLET::::- 732 Battle of Tours stops Islam from expanding westward
  
  BULLET::::- 750? Tower added to St Peter's Basilica at the front of the atrium
  
  BULLET::::- 752? Donation of Constantine, granted Western Roman Empire to the Pope (later proved a forgery)
   Christianity is the predominant religion in Europe, the Americas, and Southern Africa. In Asia, it is the dominant religion in Georgia, Armenia, East Timor, and the Philippines. However, it is declining in many areas including the Northern and Western United States, Oceania (Australia and New Zealand), northern Europe (including Great Britain, Scandinavia and other places), France, Germany, and the Canadian provinces of Ontario, British Columbia, and Quebec, and parts of Asia (especially the Middle East, due to the Christian emigration, South Korea, Taiwan, and Macau).
   Christians have made a myriad contributions to human progress in a broad and diverse range of fields, both historically and in modern times, including the science and technology, medicine, fine arts and architecture, politics, literatures, Music, philanthropy, philosophy, ethics, theatre and business. According to "100 Years of Nobel Prizes" a review of Nobel prizes award between 1901 and 2000 reveals that (65.4%) of Nobel Prizes Laureates, have identified Christianity in its various forms as their religious preference. Eastern Christians (particularly Nestorian Christians) have also contributed to the Arab Islamic Civilization during the Ummayad and the Abbasid periods by translating works of Greek philosophers to Syriac and afterwards to Arabic. They also excelled in philosophy, science, theology and medicine.
   BULLET::::- 1439 Notre-Dame de Strasbourg, highest building in the world until 1874
  
  BULLET::::- 1452 Dum Diversas, papal bull issued on 18 June 1452, credited with ushering in the West African slave trade in Europe and the New World
  
  BULLET::::- 1453 Fall of Constantinople, overrun by Ottoman Empire
  
  BULLET::::- 1455 Gutenberg Bible, first printed Bible, by Johann Gutenberg
  
  BULLET::::- 1473–1481 Sistine Chapel built
  
  BULLET::::- 1478 Spanish Inquisition established by Pope Sixtus IV
  
  BULLET::::- 1483 Martin Luther born in Eisleben
  
  BULLET::::- 1484 December 5, Summis desiderantes against Witchcraft issued by Pope Innocent VIII
   BULLET::::- 276 Mani (prophet), crucified, founder of the dualistic Manichaean sect in Persia
  
  BULLET::::- 282–300? Theonas, bishop of Alexandria (Ante-Nicene Fathers)
  
  BULLET::::- 290–345? St Pachomius, founder of Christian monasticism
  
  BULLET::::- 296–304 Pope Marcellinus, offered pagan sacrifices for Diocletian, later repented. Name in Martyrology of Bede
  
  BULLET::::- 301 – Armenia is the first kingdom in history to adopt Christianity as state religion
  
  BULLET::::- 303–312 Diocletian's Massacre of Christians, includes burning of scriptures (EH 8.2)
  
  BULLET::::- 303 Saint George, patron saint of Georgia, England and other states
  
  BULLET::::- 304? Victorinus, bishop of Pettau
   According to other scholars many converted for a whole host of reasons, the main statement of which was evangelisation by Muslims, though there were several instances where some were pressured to convert owing to internal violence and friction between the Christian and Muslim communities, according to historian Philip Jenkins.
   BULLET::::- 591-628 Theodelinda, Queen of the Lombards, began gradual conversion from Arianism to Catholicism
  
  BULLET::::- 596 St. Augustine of Canterbury sent by Pope Gregory to evangelise the Jutes
  
  BULLET::::- 600? Evagrius Scholasticus, Church History of AD431-594
  
  BULLET::::- 604 Saxon cathedral created (by Mellitus) where St Paul's Cathedral in London now stands
  
  BULLET::::- 609 Pantheon, Rome renamed Church of Santa Maria Rotonda
  
  BULLET::::- 612? Bobbio monastery in northern Italy
  
  BULLET::::- 613 Abbey of St. Gall in Switzerland
  
  BULLET::::- 614 Khosrau II of Persia conquers Damascus, Jerusalem, takes Holy Cross of Christ
  
  BULLET::::- 622 Mohammed founds Islam after fleeing to Mecca
   BULLET::::- 1579 Discovery of the holiest Russian icon, "Our Lady of Kazan"
  
  BULLET::::- 1580 Book of Concord of Lutheranism
  
  BULLET::::- 1582 St Teresa of Avila dies
  
  BULLET::::- 1582 Gregorian calendar of Pope Gregory XIII adopted at different times in different regions of the world
  
  BULLET::::- 1582 Rheims New Testament published – it later became part of the 1610 Douay–Rheims Bible
  
  BULLET::::- 1585 Jesuit scholar Francisco Ribera publishes first futurist interpretation, of the Biblical books of Daniel and Revelation
  
  BULLET::::- 1587 Toyotomi Hideyoshi expels Jesuits from Kyūshū
   BULLET::::- 1155 Theotokos of Vladimir arrives to Bogolyubovo
  
  BULLET::::- 1155 Carmelites founded
  
  BULLET::::- 1163 Construction begins on Notre Dame de Paris
  
  BULLET::::- 1168 Conversion of Pomerania – Principality of Rugia missioned by Absalon
  
  BULLET::::- 1173 Waldensians founded
  
  BULLET::::- 1179 Catholic Third Lateran Council
  
  BULLET::::- 1191 Teutonic Knights founded
  
  BULLET::::- 1204–1261 Latin Empire of Constantinople
  
  BULLET::::- 1205 Saint Francis of Assisi becomes a hermit, founding the Franciscan order of friars; renounces wealth and begins his ministry
  
  BULLET::::- 1208 Start of the Albigensian Crusade against the Cathars
   Meanwhile, the discovery of America by Christopher Columbus in 1492 brought about a new wave of missionary activity. Partly from missionary zeal, but under the impetus of colonial expansion by the European powers, Christianity spread to the Americas, Oceania, East Asia and sub-Saharan Africa.
   BULLET::::- 1128 Holyrood Abbey in Scotland
  
  BULLET::::- 1128 Conversion of Pomerania – second mission of Otto of Bamberg
  
  BULLET::::- 1130 Peter of Bruys burned at the stake
  
  BULLET::::- 1131 Tintern Abbey founded in Wales
  
  BULLET::::- 1131–1138 Antipope Anacletus II
  
  BULLET::::- 1139 Catholic Second Lateran Council
  
  BULLET::::- 1140? Decretum Gratiani, Catholic Canon law
  
  BULLET::::- 1142 Peter Abélard, Letters of Abelard and Heloise
  
  BULLET::::- 1144 The Saint Denis Basilica of Abbot Suger is the first major building in the style of Gothic architecture
  
  BULLET::::- 1154–1159 Pope Adrian IV, first (and to date only) English pope
   Since at least the legalization of Christianity by the Roman Emperor Constantine in the 4th century, Europe has been an important centre of Christian culture, even though the religion was inherited from the Middle East and important Christian communities have thrived outside Europe such as Oriental Orthodoxy and the Church of the East since the time of Christ. Christian culture has been an important force in Western civilization, influencing the course of philosophy, art, and science.
   Christianity began as a Second Temple Judaic sect in the 1st century in the Roman province of Judea. Jesus' apostles and their followers spread around Syria, Europe, Anatolia, Mesopotamia, Transcaucasia, Egypt, and Ethiopia, despite initial persecution. It soon attracted gentile God-fearers, which led to a departure from Jewish customs, and, after the Fall of Jerusalem, AD 70 which ended the Temple-based Judaism, Christianity as a religion began. 
   Section::::History.:Early Middle Ages.
  
  With the decline and fall of the Roman Empire in the West, the papacy became a political player, first visible in Pope Leo's diplomatic dealings with Huns and Vandals. The church also entered into a long period of missionary activity and expansion among the various tribes. While Arianists instituted the death penalty for practicing pagans (see the Massacre of Verden, for example), what would later become Catholicism also spread among the Hungarians, the Germanic, the Celtic, the Baltic and some Slavic peoples.
   In the 20th century, Christianity declined in influence in many Western countries, mostly in the European Union where some member states have experienced falling church attendance and membership in recent years, and also elsewhere. Secularism (separating religion from politics and science) increased. However, while church attendance is in decline, in some western countries (i.e. Italy, Poland and Portugal) more than half the people state that religion is important, and most Westerners nominally identify themselves as Christians (e.g. 59% in the United Kingdom) and attend church on major occasions, such as Christmas and Easter. In the Americas, Christianity continues to play an important societal role, though in areas such as Canada, a low level of religiosity is common as a result of experiencing processes of secularization similar to European ones. The official religions of the United Kingdom and some Nordic countries are forms of Christianity, even though the majority of European countries have no official religion. Despite this, Christianity, in its different forms, remains the largest faith in most Western countries.
   In the early Middle Ages, missionary activities spread Christianity towards the west among German peoples. During the High Middle Ages, eastern and western Christianity grew apart, leading to the East-West Schism of 1054. Growing criticism of the Roman Catholic ecclesiological structure and its behaviour, led to the Protestant movement of the 16th century and the split of western Christianity.
  
  Since the Renaissance era, with western colonialism, Christianity has expanded throughout the world. Today there are more than two billion Christians worldwide, and Christianity has become the world's largest religion.
  
  Section::::Origins.
  
  Section::::Origins.:Jewish-Hellenistic background.
   Section::::Economic development.
  
  Francisco de Vitoria, a disciple of Thomas Aquinas and a Catholic thinker who studied the issue regarding the human rights of colonized natives, is recognized by the United Nations as a father of international law, and now also by historians of economics and democracy as a leading light for the West's democracy and rapid economic development.
   Christianity in Europe
  
  Christianity is the largest religion in Europe. Christianity has been practiced in Europe since the first century, and a number of the Pauline Epistles were addressed to Christians living in Greece, as well as other parts of the Roman Empire.
  
  According to a 2010 study by the Pew Research Center, 76.2% of the European population identified themselves as Christians.
  