Is USURY A Sin? The History & Theology Of Usury/Money Lending w/ Josiah Stowe

Martin Luther wrote repeatedly on social and economic matters of his day, including critical treatises on usury and the practices of moneylenders. His writings reflect concern that usurious practices harmed Christian communities and enabled exploitation, while acknowledging practical necessities of lending. Luther's stance influenced Protestant debates and local policies toward credit, charity, and economic justice. His critiques are historically significant for understanding the intersection of Reformation theology and economic life. The body of Luther's work on the subject helped shape Protestant responses to finance and social ethics.

Augustine's sermons collect his preaching on pastoral, moral, and theological issues facing the early Church; Sermon 36 includes a forceful critique of exploitative lending. Augustine frames the usurer as morally culpable for extracting profit from the poor, urging Christian compassion and justice. His pastoral rhetoric influenced subsequent Christian condemnation of predatory interest-taking. The sermon reflects the patristic emphasis on charity and protecting vulnerable members of the community. Augustine's broader corpus shaped medieval and later Christian ethics on economic conduct and social responsibility.

John Calvin's On the Harmony of the Law examines the coherence between Old Testament law and New Testament Christian ethics, seeking consistent interpretation for Christian practice. In it, Calvin addresses economic matters like usury, arguing that prohibitions apply specifically to oppressive interest charged to the poor rather than all interest universally. His approach returns to Scripture (ad fontes) and emphasizes moral nuance and situational judgment. Calvin's writings influenced Reformed attitudes toward lending, charity, and community economics. The work contributed to Protestant theological discussions on how biblical law informs civil and moral life.

Ambrose's On the Duties of the Clergy is a fourth-century treatise offering guidance to Christian ministers on moral conduct, pastoral responsibilities, and ecclesiastical leadership. The work emphasizes personal holiness, charity, and justice, instructing clergy to care for the poor and avoid practices that would harm the community. Ambrose condemns exploitative behavior, including taking advantage of those in need, reflecting early Christian objections to usurious practices. The text influenced later patristic and medieval thought on clerical ethics and social responsibility. It remains an important source for understanding early Church attitudes toward economic ethics and pastoral care.

The Summa Theologica is a comprehensive work divided into three parts. The first part deals with God, the creation of the world, angels, and the nature of man. The second part is subdivided into two sections: the first part of the second part discusses general principles of morality and law, while the second part of the second part addresses morality in particular, including individual virtues and vices. The third part, left unfinished by Aquinas, focuses on the person and work of Christ and the sacraments. The work also includes a posthumous supplement that concludes the third part and discusses Christian eschatology. Aquinas drew on Aristotelian and Augustinian influences and aimed to integrate faith and reason in his theological arguments.