Christianity and colonialism are associated with each other by some ideas, because of the service of Christianity, in its various denominations (namely Protestantism, Catholicism and Eastern Orthodoxy), as the state religion of the historical European colonial powers in which Christians likewise made up the majority. In several regions, Christian missionaries acted as the "religious arms" of the imperialist powers of Europe, but oftentimes they also defended the rights of indigenous peoples.

According to Edward E. Andrews, Associate Professor of Providence College Christian missionaries were initially portrayed as "visible saints, exemplars of ideal piety in a sea of persistent savagery". However, by the time the colonial era drew to a close in the later half of the 20th century, missionaries were critically viewed as "ideological shock troops for colonial invasion whose zealotry blinded them", colonialism's "agent, scribe and moral alibi". Meanwhile, "differing South Asian groups who enthusiastically embraced Christianity have been mocked as dupes of Western imperialists" and criticized as being "separatist minded by their initial communities."

In some regions, segments of a colony's population were forcibly converted from earlier belief systems to the Christian faith, which colonial regimes used to legitimize the suppression of adherents of other faiths, enslavement of colonial subjects, and exploitation of land and maritime resources.Religion in the Andes: vision and imagination in early colonial Peru, S MacCormack - 1991Savage systems: Colonialism and comparative religion in Southern Africa, D Chidester - 1996Hindu-Catholic encounters in Goa: Religion, colonialism, and modernity, A Henn - 2014 Christians and Christian institutions around the world, however, also participated in anti-colonial and decolonization movements and were themselves transformed in the process.

Background Christianity is associated by some with the impacts of colonialism because religion was a justification among the motives of colonists. For example, Toyin Falola asserts that there were some missionaries who believed that "the agenda of colonialism in Africa was similar to that of Christianity". Falola cites Jan H. Boer of the Sudan United Mission as saying, "Colonialism is a form of imperialism based on a divine mandate and designed to bring liberation – spiritual, cultural, economic and political – by sharing the blessings of the Christ-inspired civilization of the West with a people suffering under satanic oppression, ignorance and disease, effected by a combination of political, economic and religious forces that cooperate under a regime seeking the benefit of both ruler and ruled."

Edward Andrews writes:

According to Lamin Sanneh, "Much of the standard Western scholarship on Christian missions proceeds by looking at the motives of individual missionaries and concludes by faulting the entire missionary enterprise as being part of the machinery of Western cultural imperialism." As an alternative to that view, Sanneh presents a different perspective arguing that "missions in the modern era have been far more, and far less, than the argument about motives customarily portrayed."

Michael Wood asserts that during the 16th century, it was almost impossible for the indigenous peoples to be considered human beings in their own right and that the conquistadors brought with them the baggage of "centuries of ethnocentrism, and Christian monotheism, which espoused one truth, one time and version of reality."Conquistadors, Michael Wood, p. 13, BBC Publications, 2000

Age of Discovery

During the Age of Discovery, the Catholic Church inaugurated a major effort to spread Christianity in the New World and to convert the Native Americans and other indigenous people. The missionary effort was a major part of, and a partial justification for the colonial efforts of European powers such as Spain, France and Portugal. The idea of European exploration and Christian expansion were synonymous with each other as European Christians' religious views and settlements in new lands were a way to convert the indigenous peoples. Christian Missions to the indigenous peoples ran hand-in-hand with the colonial efforts of Catholic nations. In the Americas and other colonies in Asia and Africa, most missions were run by religious orders such as the Augustinians, Franciscans, Jesuits and Dominicans.

In both Portugal and Spain, religion was an integral part of the state, and Christianization was seen as having both secular and spiritual benefits. Portuguese explorers would propose ideas of venturing into new territories to religious executives, which were approved based on the idea that "honor and glory will befall not only all of Christendom but also … this most sacred See of Peter." Wherever those powers attempted to expand their territories or influence, missionaries would soon follow. By the Treaty of Tordesillas, the two powers divided the world between them into exclusive spheres of influence, trade and colonization. The Roman Catholic world order was challenged by the Netherlands and England. Theoretically, it was repudiated by Grotius's Mare Liberum. Portugal's and Spain's colonial policies were also challenged by the Roman Catholic Church itself. The Vatican founded the Congregatio de Propaganda Fide in 1622 and attempted to separate the churches from the influence of the Iberian kingdoms.

Americas Jan van Butselaar writes that "for Prince Henry the Navigator and his contemporaries, the colonial enterprise was based on the necessity to develop European commerce and the obligation to propagate the Christian faith."

Christian leaders and doctrines were under suspicion of justifying and perpetrating violence against Native Americans found in the New World.Carroll, Vincent, Christianity on trial: arguments against anti-religious bigotry, p 87.

Spanish missions

Adriaan van Oss wrote:

The Spanish were the first of the future European countries to colonize North and South America. They came into the region predominantly through Cuba and Puerto Rico and into Florida. The Spaniards were committed, by Vatican decree, to convert their New World indigenous subjects to Catholicism. However, initial efforts (both docile and coerced) were often questionably successful, as the indigenous people added Catholicism into their longstanding traditional ceremonies and beliefs.

An example of the successful integration of Catholicism into longstanding beliefs is the change in the Incan religion. The Spaniards, especially, weaved Catholicism into Incan religious beliefs by altering the Andean religion to align more with Catholic teachings. That religious integration resulted from the idea that the Incan indigenous people were better Catholics than the Europeans who preached to them. The many native expressions, forms, practices, and items of art could be considered idolatry and prohibited or destroyed by Spanish missionaries, military, and civilians. They included religious items, sculptures, and jewelry made of gold or silver, which were melted down before shipment to Spain. That shows the ideology of the Spanish conquerors, who were motivated by God, gold, and glory.

The Spanish imposition of their cultural beliefs made some indigenous languages of the Americas evolve into replacing their native languages with Spanish, which are lost to today's tribal members. Priests who understood and could speak indigenous languages were more efficient in religious conversion by evangelizing in them. It was a collective effort by both groups to form a way of communication with each other as Quechua-speaking officials, and Andean officials learned Spanish.

In the early years, most mission work was undertaken by the religious orders. Over time, it was intended that a normal church structure would be established in the mission areas. The process began with the formation of special jurisdictions, known as apostolic prefectures and apostolic vicariates. The developing churches eventually graduated to regular diocesan status with the appointment of a local bishop. After decolonization, the process increased in pace as church structures altered to reflect new political-administrative realities.Hastings, Adrian, A World History of Christianity, Wm. B. Eerdmans Publishing, 2000, pp 330–349

Ralph Bauer describes the Franciscan missionaries as having been "unequivocally committed to Spanish imperialism, condoning the violence and coercion of the Conquest as the only viable method of bringing American natives under the saving rule of Christianity." Jordan writes "The catastrophe of Spanish America's rape at the hands of the Conquistadors remains one of the most potent and pungent examples in the entire history of human conquest of the wanton destruction of one culture by another in the name of religion"."In the Name of God : Violence and Destruction in the World's Religions", M. Jordan, 2006, p. 230

Antonio de Montesinos, a Dominican friar on the island of Hispaniola, was the first member of the clergy to publicly denounce all forms of enslavement and oppression of the indigenous peoples of the Americas.Hanke, Lewis. (1946) Free Speech in Sixteenth-Century Spanish America. The Hispanic American Historical Review, 26,2:135–149. Page 142. Theologians such as Francisco de Vitoria and Bartolomé de las Casas drew up theological and philosophical bases for the defense of the human rights of the colonized native populations, thus creating the basis of international law, regulating the relationships between nations.

The Native Americans only gave way to the force of the European after they were overcome with the diseases the Europeans had spread. The Evangelization of the natives in the Americas began with private colonization. The Crown tried to establish rules to protect the natives against any unjust war of conquest. The Spanish could start a war against those who rejected the kings authority and who were aware and also rejected Christianity. There was a doctrine developed that allowed the conquest of natives if they were uncivilized.

Friars and Jesuits learned native languages instead of teaching the natives Spanish because they were trying to protect them from the colonists’ negative influences. In addition, the missionaries felt that it was important to show the positive aspects of the new religion to the natives after the epidemics and the harsh conquest that had just occurred.

French missions

The Jesuit order (the Society of Jesus) established missions among the Iroquois in North America by the 1650s–1660s. Their success in the study of indigenous languages Was appreciated by the Iroquois, who helped them expand into the Great Lakes region by 1675. Their order was banished from France in 1736, but they did not entirely disappear from North America, and an American diocese was established in 1804.Daniel Hechenberger, "The Jesuits: History and Impact: From Their Origins Prior to the Baroque Crisis to Their Role in the Illinois Country." Journal of the Illinois State Historical Society 100#2 (2007): 85–109 Online.