structural:reformatting
Social and economic influences

Calvin expressed himself on usury in a 1545 letter to a friend, Claude de Sachin, in which he criticized the use of certain passages of scripture invoked by people opposed to the charging of interest. He reinterpreted some of these passages, and suggested that others of them had been rendered irrelevant by changed conditions. He also dismissed the argument (based upon the writings of Aristotle) that it is wrong to charge interest for money because money itself is barren. He said that the walls and the roof of a house are barren, too, but it is permissible to charge someone for allowing him to use them. In the same way, money can be made fruitful.

He qualified his view, however, by saying that money should be lent to people in dire need without hope of interest, while a modest interest rate of 5% should be permitted in relation to other borrowers.

In The Protestant Ethic and the Spirit of Capitalism, Max Weber wrote that capitalism in Northern Europe evolved when the Protestant (particularly Calvinist) ethic influenced large numbers of people to engage in work in the secular world, developing their own enterprises and engaging in trade and the accumulation of wealth for investment. In other words, the Protestant work ethic was an important force behind the unplanned and uncoordinated emergence of modern capitalism.

Expert researchers and authors have referred to the United States as a "Protestant nation" or "founded on Protestant principles," specifically emphasizing its Calvinist heritage.