The reference to vulnerability has become commonplace in bioethics, and its roots in Christianity run deep. But if it is exploited by the personal demand for healthcare that characterizes societies modelled by biomedical expertise, and an individualistic appropriation of available therapy, it poses a problem. The Christian communities must adapt their concept of vulnerability to form the mainspring of their engagement for health care. Reading a new Gaudium et spes allows us to de�ne a conciliar approach to the ethical aspect of vulnerability, but also to question its pertinence when individual acceptation of a social system is less than certain. The divergence incites us to mobilize the practical resources of faith, in order to found a theological ethic of vulnerability. This article explores an investigation into liturgy and reveals its richness.