INTRODUCTION: Social participation has proved to be effective in the establishment and development of civil societies, assuming great importance in this regard. The Red Crescent Society, as the largest non-governmental organization (NGO) in the country and the oldest NGO in the world, is engaged in humanitarian activities at both national and international levels through attracting and retaining volunteers and public participation. METHODS: The present practical quantitative cross-sectional field study aimed to investigate the relationship between religiosity and citizens' voluntary participation in the activities of the Red Crescent Society. The statistical population included all volunteers participating in the activities of the Isfahan Red Crescent Society, out of whom 384 cases were selected as the sample. The data were analyzed using SPSS software and structural equation modeling in SmartPLS software. FINDINGS: It can be seen that religiosity in various dimensions is one of the important sources of increasing the voluntary participation of citizens, which increases the various dimensions of voluntary participation. In this regard, it can be said that Islam especially Shia religion due to its collective nature of abundance can play a very important role in increasing the voluntary participation of citizens and the Red Crescent Society, as a non-profit public institution, can also use this capacity to advance its transcendent goals. CONCLUSION: As evidenced by the obtained results, there was a positive and significant relationship between religiosity dimensions (belief, experience, practice, knowledge, and consequences) and voluntary participation in the activities of the Red Crescent Society; therefore, all research hypotheses were confirmed. Furthermore, based on the results of the structural equation model (SmartPLS), religiosity had a moderate effect on voluntary participation in the activities of the Red Crescent Society.
