Apparently many non-religious people think that Humanist organizations are unnecessary because most culture and organizations are secular after all.
I think the point that we as Humanists are trying to make is that the vast majority of secular organizations or communities are pluralistic. They include people with religious beliefs.
Accordingly, Humanist institutions would be the only place where the atheist’s basic worldview, one that lacks supernatural beings and animation, would be explicitly shared by all or nearly all the other members. Some people need to spend part of their time in such a social, intellectual, and emotional space.
I don’t think we can frame ourselves as a mere general social outlet for people who can’t join a traditional religious organization because they do not believe in gods. Such a “generalist” could join a new-in-town group, and I believe Reform Judaism and Unitarian Universalist congregations are open to such people.
Nor can we frame Humanist community as a secular space for discussing existential issues. Such a function could be performed by, for example, an “Existential Discussion Meetup.” The problem with such a group is that it can include people talking about their relationship with God and still be considered secular because it lacks a religious focus.
In the end, Humanist community and culture refers to the specific marginalization or exclusion of believers and their perspectives. Why can’t we just say that?