It should now be apparent that all three common approaches to definition – essentialist, functionalist, and family resemblance – have problems associated with them. But don't despair; for if definition is a human action used to make the world knowable and thinkable, then one wouldn't be surprised to find that the very tools we use to define things have limitations of their own. After all, even multi-purpose Swiss army knives, complete with can openers and corkscrews, can't be used for everything. Why? Because despite doing their best to anticipate eventual needs, their designers are not all-knowing and their tools inevitably fall short because the interests of the tool's users continually evade the designer's knowledge.

What's the point? If tools are devised to accomplish interests, but if those interests are forever in motion, then the devices that we use to make the world knowable (those things that we commonly call concepts, categories, systems of classification, etc.) must continually be re-tooled – and sometimes even discarded – all depending on our ever-changing needs. So the category ‘religion’ is your tool; how will you define it and what are you going to do with it?