The main reason for the manifest destiny was the common belief among the inhabitants of the United States that American colonizers should expand in North America. This expressed the belief that the American people were elected by God to civilize their continent. That is, what motivated the manifest destiny was rugged Individualism and pioneering spirit
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One of the themes within manifest destiny is the idea of American exceptionalism. This can be traced back to American Puritanism, particularly in John Winthrop's famous sermon entitled "City upon a Hill" made in 1630, where he called for the establishment of a virtuous community that would be a shining example to the Old World. In the influential Common Sense pamphlet of 1776, the revolutionary Thomas Paine echoed this notion, arguing that the American Revolution gave the chance to create a new and better society.
There was also the influence of racial dominance, nominally the idea that the American Anglo-Saxon race (whites) was "separated, unequally superior" and "destined to bring good government, commercial prosperity and Christianity to the American continents." This view also said that the "lower races were bound to subordination or extinction." This was, for example, used to justify the enslavement of blacks and the expulsion or extermination of Native American Indians
