"A common or longstanding belief, custom, or catchphrase associated with a particular group, especially one with little current meaning or truth." (Wiktionary).
If you mean to restrict it to the Biblical usage of pronunciation, it generalized past that centuries ago.
Please don't be a jerk on HN, no matter how limited someone's English is or you feel it is. Posts like this only make things worse, whether you're right or not.
HN doesn’t really distinguish between “punching down” and “punching up”, and prefers to avoid “punching” at all.
The guiding principle to keep top of mind is “intellectual curiosity”. There’s a place for an intellectually curious discussion about the history and present day meaning of the word “shibboleth”, and the way you commented brings that to a screeching halt. And even if someone else seems to be acting like a bit of a jerk in the comments, it doesn’t make it OK to do it too.
But as you say, you’ll try to do better which is great.
And it has become a convenient shibboleth: anyone using the word that way has nothing of value to say to me on any topic.