The purpose of this study is to investigate how religious ethics, while retaining its identity, can contribute to political debate and to the understanding of justice. The inquiry addresses these issues by focusing on theological perspectives which challenge the solutions offered to these questions by the liberal paradigm. Three kinds of challenges are studied, each of which is represented by one thinker from the Islamic tradition and one from the Christian tradition, in order to enable a comparative perspective on the contributions of religious traditions. The thinkers studied are: 1) modified liberalism, represented by Abdullahi Ahmed An-Na’im and Duncan B. Forrester; 2) liberationism, represented by Ali Shariati and Gustavo Gutierrez; and 3) radical traditionalism, as developed by Tariq Ramadan and John Milbank. The study is organized around three main questions. First, how can innovative interpretations of religious tradition be plausibly justified? Second, what role should religious arguments and reasons play in the political sphere? Third, what can religious ethics and theological thought contribute to the understanding of social justice? The questions are engaged by means of a critical and reconstructive engagement with the six thinkers. The suggested solutions are assessed in terms of the criteria of authenticity, communicability, and potential for transformation. It is argued that a religious ethic can rely on a tradition without accepting conservative understandings of that tradition. Furthermore, it is argued that the coherence of religious ethics can be made available for public discourse but that the hospitability of the public forum to such contributions needs to be realized through a deepened democratic culture and a critique of power structures which condition perceptions of rationality. While religious ethics do not articulate complete alternative understandings of justice, they articulate contributions by relating justice to human sociality and to transcendence.