Faith-based teachings on the environment have been identified as a potentially effective form of conservation outreach but one that remains largely untested. Indonesia contains 10% of the world's tropical rainforests and is the most populous Muslim country. A faith-based approach to conservation could therefore yield significant conservation benefits here. Within Islam several key principles in the Qur'an underpin and outline the role of humans in nature conservation. Here, we report on a Darwin Initiative project component that sought to assess the applicability of Islamic teachings to conservation action in West Sumatra. We developed water-conservation-themed sermons that were delivered by project-trained religious leaders in 10 mosques and nine Islamic boarding schools during the holy month of Ramadan. We conducted entry–exit questionnaire surveys to assess levels of concern, awareness and intent to act amongst male (n = 389) and female (n = 479) worshippers. The results revealed that greater attention should be paid to raising awareness of the linkages between Islam and conservation rather than on conservation principles alone, which were already adequately understood. This study provides the first insights into the important role that women could play within a faith-based project. Female respondents demonstrated greater knowledge and understanding of Islamic teachings about the environment and the services provided by watershed forests. They were also more likely to contribute to conservation activities, suggesting that future projects should seek to involve this often marginalized stakeholder group fully, as well as provide practical ways for men and women to transform words into action.