People can be passionate about language as they are about religion, sometimes the two intersect. For example linguist sometimes describe a word as a shibboleth. Saying something as shibboleth means the word tags you as a member of certain group or class. For example, if you say irregardless, it tags you as someone who poorly educated or does not use proper language.
Shibboleth is a Hebrew word, and its linguistic meaning stems from biblical story of Gileadites. Who used the word to identity Ephraimites. The Ephraimites can not pronounce the "sh" sound, so shibboleth came out sounding wrong, making them instantly identifiable.
intersect: meet at a point
identifiable: capable of being identified