Later, the Church and its philosophers, especially St. Augustine and St. Thomas Aquinas, were completely absorbed with the question of immortality. These religious thinkers emphasized salvation as the all-important concern of society and criticized the acquisition of earthly material goods or riches. And so it was that the New Testament phrase "For the love of money is the root of all evil" (I Timothy 6:10) blocked the development of the market system, which emphasized self-gain and profit rather than spirituality.
Gradually, however, the factors listed above helped shape the market system. The Renaissance encouraged a new individualism in economic affairs and contributed to the breakdown of the guild system and to the rise of enterprise. Protestantism became a strong force in the alteration of concepts. Calvinism especially encouraged enterprise. Some Calvinists saw prosperity as a sign of God's grace, and poverty as evidence of damnation. Thus the Protestant Reformation obliterated the old concept of the just price and the ban against charging interest on loans. Consequently, the loaning of money and the investment of capital became respectable, and Western society as a whole adopted the profit motive, an idea explained by Adam Smith, the father of modern economics.
