Even the word religion has debatable origins. A popular etymology involves related roots - ligare or link and legere or gather and legio or read/ponder. Perhaps you can see that they are all about connections. I prefer 'relink' or 'link to the past'.
Be that as it may, besides the obvious distinctions (see - metaphysics and no visible means of support), what are the similarities and differences at the root of these words/concepts: