Launched in 2002 as an initiative of the office of the Archbishop of Canterbury and since 2013 under the stewardship of Georgetown University, the Building Bridges Seminar--a gathering of scholar-practitioners of Islam and Christianity--convenes annually for deep study and discussion of selected texts pertaining to an overarching theme such as scripture, prophethood, science and religion, and prayer. This book digests the proceedings of the thirteenth annual Building Bridges seminar, convened in and near Washington, DC in April 2014, during which a distinguished group of Muslims and Christians explored questions of sin, forgiveness, and reconciliation. Part I provides the complete texts of the opening lectures by Veli-Matti Kärkkäomen and Jonathan A.C. Brown. Parts II-IV feature essays on the core concepts identified in the seminar theme, with contributions by Christoph Schwöbel, Ayman Shabana, Susan Eastman, Mohammad Hassan Khalil, Philip Sheldrake, and Asma Afsaruddin. In the concluding section Lucinda Mosher shares anecdotes and insights from the plenary and small-group discussions.