I'll second this. A book club, or any other gathering I've experienced (and I've searched frantically), pales in comparison to the 'smallgroups' that were part of my religious world. The closest I came to that experience in a non-religious way were some of the Alain de Botton style 'Church for Atheist'
meetups. And even then only the ones that were organized by an overtly religious person!
But a community centered around a particular framework, with a particular set of goals that extend beyond even the lifespan of the people involved, combined with an outlet for collective grief/ecstasy. It's hard to describe if you haven't grown up in it, but it's different from any other community I've experienced.