I have no religious affiliation but would like to offer Passover greetings to my close Jewish friends. What would be a proper greeting?
“Happy Passover” would be appropriate. If you want to sound really with-it, say “Happy Pay-sach” (“sach” rhymes with “Bach”, as in Johann Sebastian). If you’re really daring you can try the traditional greeting of “Chag Kasher V’Sameach”, which means “Have a Happy and Kosher Holiday.”
This reminds me of the story of someone who made their best attempt to say this traditional greeting but it came out as “I hope you all have a Happy and Kosher Hog!”
...as I said, “Happy Passover” is sufficient.