- the development of the members' spirituality
The other purpose of the church is to foster community, so we have people with whom to learn, to celebrate, to mourn, to share daily joys and sorrows, to learn, to play, to share food, to raise children.
But for the person who is growing faster spiritually than the community is growing, these two begin to feel like they are antithetical to each other. That is, I want to be part of the community, because of the warm feeling and support I feel as part of it, but it limits my spiritual development, because to stay at one with the community, I have to develop more slowly than I'd really like to develop, or maybe not develop at all. What I choose depends on which is my higher priority -- my development or my participation in the community. So if it's more important to me to grow spiritually, then I'll move on, perhaps to another community, or perhaps to none at all. If it's more important to me to have community, I will either compromise my development, or hide my development.
This dichotomy plays out for the church as a whole, too. Each church member's spiritual development happens at its own pace -- some don't develop at all, others bound ahead, still others grow at a moderate pace in their understanding. So at what rate does the community as a whole develop? Generally not with those who are changing the fastest. Perhaps it develops at the rate of the slowest, or perhaps at the rate of the bulk of the members. Whatever rate it changes at, will not suit everyone.
But community thrives on stability and with numbers -- the more people who are in the community, the more there are for the support of all in good times and bad. The longer they are there, the more trust there is among them, and therefore the group is stronger, too. So it is natural for the community to want to keep people to keep them 'in the fold'. That means keeping them growing (or even not growing) spiritually at the same rate, which will, by definition, be inappropriate for some members. The means people will keep coming and going as they match the spiritual intent/level of the church. But it's bad for community to have constant change in its membership.