A huge amount of language in the western world is based around biblical stories, and you need to know dozens of them to understand common idioms and metaphors.

A huge amount of language in the western world is based around biblical stories, and you need to know dozens of them to understand common idioms and metaphors. From the snake in the garden of Eden to being the David to someone's Goliath, to being a good Samaritan, to camels going through the eye of a needle (and here's dozens more https://city.org.nz/blog/eo-bible-20181101 https://city.org.nz/blog/eo-bible-20181101). Beyond that, especially in English, the King James bible's phrasing of dozens if not hundreds of biblical passages are now common turns of phrase - where not knowing their origin reveals you as a uncultured. Same as Aesop's or La Fontaine's fables, really -- you know it's fiction, you don't have to think it is a good story, you don't even have to agree with the morale -- but since everyone literate in the last two centuries is familiar with it, you will look out of place not knowing it.