There are some concepts so significant that when they begin to lose their meaning, individuals and groups can feel their own identity and value slipping away. their remaining energy is either  directed towards internal concerns or seeks alternative goals to restore a sense of relevance.
The Catholic Church has an example, and warning, of this in what has happened to the Irish missionary movement. Like the birds that miners brought underground with them to alert them of lethal gases, missionary enthusiasm is the first to suffer from a sudden deterioration in the religious atmosphere.