Tourism related to religious sites and festivals, pilgrimage and spirituality is considered an extremely important sector of the tourism market. The true value of religious sites lies in supporting basic tourism products outside pilgrimage destinations, as churches, cathedrals and monasteries attract many visitors, including those who are not travelling for religious purposes only. For tourists who are not driven by religious motives, religious sites are no different than any other tourism attraction – they need to attract tourists’ attention in order for them to decide to include those sites in their future trip. Therefore, appropriate promotion of religious sites is equally important as promotion of any other tourism product. Since modern promotion has mostly relocated from the traditional to the digital stage, this paper offers research on the frequency of promoting religious tourism sites on Facebook by the National Tourism Organisation of Serbia compared to the frequency of promoting religious tourism sites by the NTOs of the defined competitive set, that is, NTOs of Slovenia, Bulgaria, Hungary, Czech Republic and Slovakia. In order to provide more in-depth analysis, the frequency of promoting religious tourism sites on Facebook by the four European countries with the highest number of religious sites on the UNESCO World Heritage List was analysed, that is, NTOs of Italy, Spain, Germany and France. The study presented in this paper is focused on promotion of religious sites to all types of tourists, not only the religiously motivated ones. For the purpose of the research, all posts published by the official Facebook pages of the analysed NTOs during the period of one year were analysed. The research provides valuable insight into the frequency of promoting cultural tourism attractions and determining how many cultural tourism attractions promoted were religious sites. The posts promoting religious sites were analysed in more detail, therefore the most frequently promoted religious sites by the analysed NTOs were determined, the type of content used in order to promote them, as well as the level of interactivity of the posts promoting religious sites. The most important contribution of the research presented are the data on the engagement rate of the posts promoting religious sites compared to the overall engagement rate of the posts published by the analysed NTOs.