Final answer:
To justify imperialism, the United States stated it was their duty to spread Christianity among the heathen, particularly during the period of the 'Civilizing Mission.' This was part of an ideology that conflated Christian ethics with American virtues, spread zealously by missionaries.
Step-by-step explanation:
To justify imperialism and the expansion of their influence, many industrialized nations believed it was their duty to spread Christianity among the heathen. This ideology was especially prominent in a number of Western countries, where religious conversion and the spread of Western culture were seen as integral to the colonial project. The nation that openly stated it was their duty to spread Christianity among the heathen as a part of their imperialistic endeavors was c- The U.S.
In this context, the United States saw the expansion of democracy and Christian values as intertwined with the concept of the "Civilizing Mission." Influential Americans were convinced that as they extended their territory, they invariably brought Protestant institutions along, offering a new way of life to the native inhabitants. This sentiment was fueled by a conflation of Christian ethics with American virtues where both were spread with zealous enthusiasm by missionaries.