Within both positive psychology and the psychology of religion and spirituality (R/S), forgiveness and hope are considered key virtues or character strengths. When relationships are beset by transgressions, engaging in forgiveness is related to hope that the relationship is repairable. When people participate in forgiveness interventions, they increase their hope. There are religious and spiritual, empirical, and theoretical reasons why forgiveness and hope are interrelated. We explore these reasons using an evidence-based theoretical model of forgiveness and relational spirituality, which is at the intersection of positive psychology and the psychology of R/S. The forgiveness and relational spirituality model combines basic and intervention research to conceptualize how R/S is related to forgiving. The model posits a sacred dimension to the interrelationships among the victim, offender, and transgression, which are embedded in a particular forgiveness-relevant event. We incorporate hope into this theoretical model and review recent scientific research (2012–2020) on hope, forgiveness, and R/S conjointly (k = 27) and on forgiveness and R/S specifically (k = 72). Almost all this research has been cross-sectional and correlational. We hypothesize causal connections to guide future research and propose ways to guide practitioners as they help people navigate relational forgiveness with more hope.