This paper discusses the role of religions and specifically, religious leaders, in peacebuilding. To achieve the purpose, in the first place, the authors shed light on the controversial issue among scholars perceiving religion more commonly as a source of conflict, or rather than a tool for peacebuilding. Accepting the constructive and productive role of religions in general, and Islam in particular, in peacebuilding, the paper also explores the role of concepts such as forgiveness, patience, and human dignity in peacebuilding. Having applied this conceptual framework, this article studies peacebuilding in post-war Iraq. The findings revealed that the role of religious leaders (Marjaiah), mainly Ayatollah Sistani, has been significant in the process of peacebuilding in Iraq. He has played a crucial role in this process through the revival of human dignity in light of public will, pursuing justice in terms of the Constitution, self-restraint as a basis for political stability and, religionization of forgiveness and tolerance. Data is accumulated through content analysis of Ayatollah Sistani’s speeches and Fatwas.