Kekristenan pada abad ke-20 diwarnai oleh sekulerisasi masyarakat Barat, yang dimulai pada abad ke-19, dan penyebaran agama Kristen ke wilayah non-Barat di seluruh dunia.

Ekumenisme Kristen makin berpengaruh, bermula pada Konferensi Misionaris Edinburgh tahun 1910, dan berpuncak setelah Konsili Vatikan Kedua dari Gereja Katolik. Gerakan liturgi menjadi signifikan dalam gereja Katolik dan Prostestan, khususnya Anglikan.

Pada saat yang sama, ateisme yang dipromosikan negara di Eropa Timur komunis dan Uni Soviet menimbulkan penindasan terhadap banyak umat Ortodoks Timur dan Kristen lainnya. Beberapa Ortodoks datang ke Eropa Barat dan Amerika, berujung pada peningkatan besar kontak antara Gereja Barat dan Gereja Timur. Meskipun demikian, orang yang datang ke gereja makin turun di Eropa Barat ketimbang Timur. Gereja Katolik Roma mengadakan banyak reformasi dalam rangka modernisasi. Para misionaris Katolik dan Protestan juga mendatangi Asia Timur, meningkatkan keberadaan dan kegiatan mereka di Korea, Tiongkok daratan, Taiwan, dan Jepang.

• Anderson, Gerald H.,, ed. (1998), Biographical dictionary of Christian missions, Simon & Schuster Macmillan 
• Barrett, David, ed. (1982), World Christian Encyclopedia, Oxford University Press 
• Duffy, Eamon (1997), Saints and Sinners, a History of the Popes, Yale University Press in association with S4C, Library of Congress Catalog card number 97-60897 
• Franzen, August; Bäumer, Remigius (1988), Kleine Kirchengeschichte, Freiburg: Herder 
• Fontenelle, Mrg R (1939), Seine Heiligkeit Pius XI., France: Alsactia 
• Gailey, Charles R.; Culbertson, Howard (2007), Discovering Missions, Beacon Hill Press of Kansas City 
• Glover, Robert H.; Kane, J. Herbert (reviser) (1960), The Progress of World-Wide Missions, Harper and Row 
• Herzog, Johann Jakob; Schaff, Philip; Hauck, Albert (1910–1911), The New Schaff-Herzog Encyclopedia of Religious Knowledge (edisi ke-12 volumes), Funk and Wagnalls Company 
• Kane, J. Herbert (1982), A Concise History of the Christian World Mission, Baker 
• Latourette, Kenneth Scott (1938–45), A History of the Expansion of Christianity (edisi ke-7 volumes) 
  • Latourette, Kenneth Scott (1941), A History of the Expansion of Christianity, IV and V 
• Moreau, A. Scott; Burnett, David; Engen, Charles Edward van; Netland, Harold A. (2000), Evangelical Dictionary of World Missions, Baker Book House Company ^{[perlu rujukan lengkap]}
• O'Brien, Felictity (2000), Pius XII, London  ^{[perlu rujukan lengkap]}
• Olson, C. Gordon (2003), What in the World is God Doing?, Global Gospel Publishers 
• Parker, J. Fred (1988), Mission to the World, Nazarene Publishing House 
• Riasanovsky, Nicholas V. (1963), A History of Russia, New York: Oxford University Press 

• Farrell, Joseph P. God, History, & Dialectic: The Theological Foundations of the Two Europes and Their Cultural Consequences. (1997)
• González, Justo L. (1985), The Story of Christianity, Vol. 2: The Reformation to the Present Day, San Francisco: Harper, ISBN 978-0-06-063316-5 
• Hastings, Adrian (1999), A World History of Christianity, Wm. B. Eerdmans Publishing, ISBN 978-0-8028-4875-8 
• Nichols, Aidan. Rome and the Eastern Churches: a Study in Schism. 1992
• Shelley, Bruce L. (1996), Church History in Plain Language (edisi ke-2nd), ISBN 978-0-8499-3861-0 

• Ahlstrom, Sydney E. A Religious History of the American People (1972, 2nd ed. 2004); widely cited standard scholarly history excerpt and text search
• Angold, Michael, ed. The Cambridge History of Christianity: Volume 5, Eastern Christianity (2006)
• Callahan, William J. The Catholic Church in Spain, 1875–1998 (2000).
• Gibson, Ralph. A Social History of French Catholicism 1789–1914 (London, 1989)
• González Justo L. and Ondina E. González, Christianity in Latin America: A History (2008)
• Hastings, Adrian. A History of English Christianity 1920–2000 (2001)
• Hope, Nicholas. German and Scandinavian Protestantism 1700-1918 (1999)
• Lannon, Frances. Privilege, Persecution and Prophecy: The Catholic Church in Spain 1875–1975 (1987)
• Lippy, Charles H., ed. Encyclopedia of the American Religious Experience (3 vol. 1988)
• Lynch, John. New Worlds: A Religious History of Latin America (2012)
• McLeod, Hugh, ed. European Religion in the Age of Great Cities 1830–1930 (1995)
• Noll, Mark A. A History of Christianity in the United States and Canada (1992)
• Rosman, Doreen. The Evolution of the English Churches, 1500-2000 (2003) 400pp

• History of Christianity Reading Room: Extensive online resources for the study of global church history (Tyndale Seminary).
• Dictionary of the History of Ideas: Christianity in History di Archive.is (diarsipkan tanggal October 16, 2007)
•  Phillips, Walter Alison (1911). "Church History". Encyclopædia Britannica. 6 (edisi ke-11). hlm. 330–345. 
• Historical Christianity, A time line with references to the descendants of the early church. di Wayback Machine (diarsipkan tanggal February 2, 2007)