> A membership community with secrets and opportunities reserved for members.
That can also be a guild.
"Cult" is a term from the study of religion (a particular field's jargon, if you will), and usually conveys intense devotion, a ritual or sacrificial dimension that goes beyond a master craftsman's level of devotion to a craft.
Also, a guild can't entertain fanciful ideas about their craft for too long, if the ideas don't work in practice.
The distinction is kind of like using Cobol to build a good solid system (guild), versus dropping some Lisp to reach enlightenment (cult), or using C to build a solid system (cult).
In which case, I'm voting cult all the way.