In this paper I will address the dif?cult problem of the legitimacy of the corporations in modern society from the perspective of the relation between economics and religion. The article starts out from the work on Protestant Ethics of Max Weber and it continues with a presentation of the interesting book of the Princeton economist Robert H. Nelson: Economics as Religion: From Samuelson to Chicago and Beyond, Pennsylvania State University Press, United States, 2001. Accordingly the paper is mostly a book review of Nelson's argument. I think that the work of Nelson is an important challenge for understanding social legitimacy of economics. With Nelson we can introduce the viewpoint in economics known as “institutional economics” as a way that the corporation can be open to its institutional and systemic environments. In the last part of the paper, I confront Nelson's criticism of economics as religion and I propose a concept of economics based on a democratic conception of the firm conceiving the economic and social legitimacy of the ?rm as based on the idea of communicative business ethics. Communicative business ethics can be conceived as based on a concept of the firm as an open cybernetic system as being in dialogue and interaction with its environment. This concept of the firm avoids the deadlock of economics as religion that captures most of the predominant concepts of economics and of the position of the firm in modern society.