This study aimed to address two key theoretical gaps in the service management literature: (1) the full mediating role of service quality in the relationship between Islamic spiritual intelligence (ISI) and customer satisfaction, and (2) the impact of the religious-cultural context on redefining the service-profit chain. Conducted as an applied, descriptive-correlational study, data were gathered from 250 customers of five-star hotels in Mashhad using a 45-item questionnaire. The data were analyzed via Partial Least Squares Structural Equation Modeling (PLS-SEM) using SPSS and SmartPLS software. The findings indicated that both Islamic emotional intelligence and ISI exert a direct influence on service quality. Service quality, in turn, was a strong predictor of customer satisfaction and loyalty, respectively. The analysis confirmed the full mediation of service quality between the intelligence constructs (emotional/spiritual) and satisfaction, and the full mediation of satisfaction between service quality and loyalty. Conversely, the direct paths from the intelligence constructs to satisfaction/loyalty were found to be insignificant. These results led to the development of a "Spiritual Service-Profit Chain" framework, a redefinition of the Heskett model, and the design of a "Halal Plus" model incorporating specific practical initiatives: (1) an ISI certification for managers emphasizing components like anger management (‘Kazm-e Ghaiz’) and trustworthiness (‘Amanat’), (2) the establishment of a rating system, and (3) software for monitoring religious commitments. The study concludes that ISI acts as a strategic asset, shaping customers' faith-based loyalty through enhanced service quality, and recommends extending this model to other belief-sensitive industries