Abstract Background Despite the efforts of health authorities, vaccination coverage of targeted child populations is still poor in many regions. Parents' reticence has been identified as one cause of this situation. However, there is little data to explain the phenomenon that could support decision-making. Objective The objective of the study was to uncover the determinants of this reticence toward vaccination among the religious population of the cities of Parakou and Cotonou in Benin. Methods This was an exploratory study using a qualitative survey of 12 pastors and 30 faithful from churches that are vaccination-reticent and a control group of the same number of faithful belonging to other churches, all Christian. Individual and group interviews were carried out in the local language using a pre-established and pre-tested guide. The data collected underwent discourse content analysis focused on specific themes. Results Analysis of the data reveals an erroneous perception of child vaccination. Those who are reticent say vaccination goes against the will of God, that it is a poison from the "white witch doctor", and that those who vaccinate their children are committing a sin. Members of the control group argued against this, but without conviction. They adhere to the principle of obedience to authority, a biblical precept invoked when the vaccinators oblige them to vaccinate their children. Other factors were identified that could explain the reticence, such as the tactlessness of the vaccinators, parents' previous experiences and false rumours about vaccination. Conclusion The reasons for reticence are mainly related to parents' beliefs in religious principles that are sometimes poorly understood. To limit the spread of this phenomenon, more detailed information and negotiation between the health authorities and the pastors of these churches are essential. Abstract in French See the full article online for a translation of this abstract in French.