When did it originally become popular to say “gesundheit” in response to a person’s sneezing. I presume this originated and was popularized in German society. Is this correct? During which time period, and why? Why for example did they choose to say gesundheit, which means health, rather than something about God like “bless you”?
You should probably clarify: are you asking about when “Gesundheit“ became a common response to someone’s sneeze within German-speaking contexts, or when that expression became adapted into English?
As a follow up: many languages just use their word for ‘health’ in this context. The religious expression typical in English seems more the exception then the rule. How did this develop, since, for example, Romance languages have far more religious expressions used in everyday speech overall?