The story
From Holy Bible (King James Version), 1 Corinthians 9:22: "To the weak became I as weak, that I might gain the weak: I am made all things to all men, that I might by all means save some."
Etymology from Wiktionary, CC BY-SA 4.0.
all things to all people
Today it means: Someone or something that entirely satisfies the expectations of everyone, no matter how diverse and conflicting those expectations may be. Full definition →