I think certain people are desperate to create an identity because they rejected their past identity (became atheist for example). I don't really understand why people are so militant about these things either. I don't drink normally but I'll drink on occasion (with my colleagues for example). Because of this I never get questioned if I decide to stick with water on a particular occasion. My colleagues don't feel like it isn't perfectly valid and it requires none of the (perceived) virtue signalling on my part.