Europeans used religion to justify their actions in many different ways. One motive for the exploration and colonization of the Americas was the need to win converts to the Catholic Church in the midst of the Protestant Reformation. Many observers, both contemporaries, like Bartolome de las Casas, and later historians, argued that violence and cruelty practiced by settlers against Native Americans was inconsistent with these religious motives. Europeans were more interested in plundering the Native peoples they encountered than in bringing them religion.

Still, the idea of converting Native peoples was a consistent justification for colonization. One early promoter of the English settlement at Jamestown exhorted the colony to "let Religion be the first aim of your hopes," and to "propagate the Gospel of Jesus Christ" among the Native peoples of North America. The seal of the Massachusetts Bay Colony featured a Native American man exhorting Englishmen to "come over and help us." Spanish and French religious orders, including the Jesuits, went to great lengths to convert Native peoples. They established monasteries and missions in the far-flung corners of North and South America. Europeans believed that the benefits of Christianity justified the brutal means of conquest.

Some colonizers even argued that Native Americans were outside the reach of civilization. Their uncultured status relieved Europeans of the responsibility to treat them as human equals. This argument was famously made at the "Valladolid debates," in which Spanish theologan Juan Ginés de Sepulvéda claimed that Indian peoples were "barbarians." Any war or violence against them was just due to their "barbaric" nature.

It is easy, considering all the examples of brutality and greed in Europeans' dealings with Native Americans, to dismiss assertions of religious motives as hollow justifications for stealing land and wealth. But in reality, Europeans did not make these distinctions between religious and pecuniary motives. Many would have seen the desires to gain wealth and spread Christianity as reinforcing aims, rather than exclusive ones.

During colonialization, Europeans frequently used Christian beliefs and principles to justify their actions. The most obvious way in which Christianity was used as justification is colonialization itself. Whilst, naturally, the gain of new land and new resources was the financial incentive of conquering other countries, Europeans often claimed that their main motivation was to bring an improvement of life to the native people of these countries, as they considered the native people underdeveloped and uncultured.

Given that the people in the “New World” were not Christians, Europeans took that as a sign of these people being uncivilized. Therefore, by conquering these countries, Europeans were able to spread the Christian faith and therefore were able to tell themselves that their conquest, despite all its cruelties, was actually a blessing in disguise. We can see this very clearly in the work of Kipling, for example, whose poem “The White Man’s Burden” illustrates this way of thinking.

Indigenous people were often seen as childlike, due to their lack of understanding of the Christian faith and therefore their perceived lack of cultural maturity. Therefore, Christian religion was used to justify the need to impose European lifestyle, values and customs onto these countries: it was seen as a way to help the native people become more civilized.

At the same time, the indigenous cultures and customs were severely restricted, often banned completely, especially if they were seen in clear contradiction to the Christian faith. This helped justify the strict and severe punishment of those indigenous people, who were often caught exercising their traditional beliefs instead of Christian faith.

Religion was an important factor in European actions in the New World. Many Europeans saw the New World as a Garden of Eden, the potential of which was being wasted by the native groups who lived there. The English Puritans saw tilling the soil and bringing their own brand of civilization to the region as part of their holy mission.

Bringing Christianity to every continent was the goal of pious Europeans. Some believed that Christ would not return and fulfill the prophecies of Revelation until everyone had a chance to hear the Gospel. Missionaries also were trying to recruit converts to their brand of Christianity. This was especially important at a time when wars between Catholics and Protestants divided Europe.

Spanish missionaries viewed native groups of Central and South America as especially savage. They destroyed their texts and statues because they considered them to be inspired by the devil. They killed any who did not convert. Those who did convert were forced to work on haciendas or in mines for nothing, as enriching the Spanish Empire was to be their way of serving God. French Jesuit priests took a more liberal approach to conversion, often translating Bibles into Indian languages. France claimed a large portion of the New World due to the work of their priests.