Ceremonies are important- every human culture has them. They mark our passage through life, from birth, through adulthood, marriage, parenthood and death. Without them, your post-apocalyptic society may not collapse, but it will lack cohesion- it will be less of a society, and more of a loose collection of individuals. It’s time to think ceremony.
Now, there won;t be the time and resources to perform the ridiculous, over-ornate and costly ceremonies that exist in the west, but ceremonies will still need to exist. ANd as a leader, you will probably have to lead them, in order to solemnise them and make them seem legitimate in the eyes of your followers. Cermonies have another advantage, one the church exploited in medieval europe- if someone misbehaves, you can restrict their access to these necessary markers, effectively making them a non-person. Cunning, hey?