Does anyone remember the title of a short story about a grocery list that becomes a worshipped religious artifact?

I believe you are thinking about A CANTICLE FOR LEIBOWITZ by Walter Miller, which started out as a short story and was later turned into a great novel in 1959. (The list read, "Pound pastrami, can kraut, six bagels. Bring home for Emma.")

That novel is a very good novel. I thoroughly enjoyed it!