BTW the 23% of the worlds population that are christians and the far more 2 plus billion that are Muslims all believe in the concept of Yom Kippur since they blieve in the “Old Testament” they just believe they superseded it or got it wrong depending which one.
A widespread disbelief in Har Sinai in what is termed the “Developed World” is kind of a new “happening” starting about 250 years ago.
Sort of like the Mabul, archeologists reveal a pretty widespread story amongst anient civiliztion with a core that revolved around the world being destroyed by a flood and one man being saved and saving the animals with him (ex. Thee Epic of Gilgamesh) it’s a recent post enlightment development that there are those who wish to dispute it.