The church is like a lazy river.
There are two things here:
First, people can step away from the church for a while, and like the river that runs around the water park, the church keeps moving. This can be hard at times, and even sad, watching people exit the flow of parish life.
Second, people can re-enter after a while, and like the river that runs around the water park, the church doesn’t ask them to swim back upstream to make up for lost time. There is no make-up work in the life of the parish, only the invitation to get back in and ride along.
There is grace in that river.