Most people use "religion" to mean "organized religion" in particular, and many people further take it to mean christianity and christianity-like religions. Religion is a word that is hard to define, but I think that although there are many edge cases, most people mostly agree on what is and what isnt a religion. My point here is that, just because they are not definable in a strict sense, does not mean the words "religion" and "faith" are "pointless". They very much have meaning.

Many words are like that: no clear definition but they refer to real things or ideas. For example, existentialism, postmodernism, artistic styles (such as cubism or impressionism), etc. And even many terms in the sciences are like that. None of the words mathematics, physics or philosophy have clear-cut definitions. Hell, i can take this to the extreme. Even words like water or gold do not have a clear definition, in the way that lay people use them. Seawater is water even though it is made up of more than just H2O. 95% ethanol is never called water, even though 5% of it is water.