Based on the conservation of resources theory, this study developed a model linking social undermining to employees helping behaviors and work role performance via expression of guilt, with religious faith possessed by employees as a first-stage moderator. We argue that individuals will feel guilty if they perceive themselves as the perpetrators of the social undermining against their coworkers. Feeling guilt can potentially trigger prosocial responses (i.e., helping coworkers) and enhance work role performance for improving the situation. We contend that religious (...) faith that commands doing good with others further provides resources for managing these negative emotions to unleash a positive side of social undermining, such that the relation of social undermining with an expression of guilt will be strengthened. A multisource (supervisor-supervisee), multi-wave, and multi-context (education, healthcare, and banking) survey involving 281 employees largely supports our study hypotheses. The results indicated that social undermining is associated with more guilt expressions amid religious individuals, revealing higher prosocial and work role performance. For business ethics research, the current study unveils an important mediator—guilt expressions about wrongdoing—via which individuals’ social undermining behaviors at work, somewhat counterintuitively, lead to boost performance outcomes, and an employee’s religious faith helps a facilitator of this relationship. (shrink)