People who hold none of the associated beliefs still mark births, deaths and transitions with inherited ceremonies. The persistence is not inconsistency; most of what ritual does works independently of what participants believe.
Ritual marks boundaries that are otherwise invisible
Transitions in a life — becoming an adult, entering a partnership, losing a parent — are gradual internally and have no natural moment at which they can be said to have occurred.
A ceremony imposes a specific point, publicly witnessed, at which the previous status ends and the new one begins.
Without such a point people often report a change feeling unreal or incomplete for a long period, which is why improvised markers appear where formal ones have been abandoned.
Fixed form removes the burden of improvisation
The situations ritual covers are exactly those in which people have least idea what to do or say, particularly around death.
Inherited form removes that problem entirely: the words are supplied, the order is known, and nobody has to decide anything while distressed.
This is why grief is one of the last areas where ritual survives, and why its absence is felt sharply by people with no belief in what the words assert.
Repetition is what makes it collective
Doing the same thing, in the same way, alongside others who have done it before produces a sense of continuity that argument and explanation do not.
Synchronised action — singing, standing, moving together — has measurable effects on how connected participants feel to one another afterwards.
Those effects depend on the coordination rather than on what the words mean, which is why they appear at secular gatherings with similar structures.
Repetition also affects the individual performing it
A repeated action performed at fixed times becomes a structure that holds a period of time in place, which is much of what daily observances provide.
The structure survives moods and doubts, so it continues to function during exactly the periods when motivation and conviction do not.
People who describe keeping a practice while having lost the belief are usually describing this, and it is a coherent position rather than a hollow one.
What is lost when only the form remains
Form separated from meaning tends to erode, because nothing explains why this particular sequence rather than any other, and modifications accumulate.
Newly invented ceremonies often struggle for the opposite reason: they carry meaning the participants chose but lack the weight that comes from having been done before.
The tension between those two is the practical difficulty facing anyone trying to mark a transition without the tradition it was formed in.