The Historical Evolution and Conceptual Challenges of Defining 'Religion'

We tend to think of religion as an age-old feature of human existence. So it can be startling to learn that the very concept dates to the early modern era.

What you don't find is a term that quite maps onto 'religion'.

Their notion of religio once meant something like scruples or exactingness, and then came to refer, among other things, to a scrupulous observance of rules or prohibitions, extending to worship practices.

Despite centuries of trying, the term 'religion' has proven impossible to define. Then why does it remain so necessary?