So I'm Grabbing Some Cheese At The Grocery Store...

[many a good man]

208. I like your point, but let me ask you a question

I'm also uncomfortable when a total stranger uses religious language in a neutral context but what is an appropriate response?

I may not feel comfortable advertising to the world that I'm a non-believer in this kind of public context. I shouldn't have to - unless I felt like it at the time. But I would like to educate the cashier that her assumptions can make people uncomfortable. It's not "shoving" anything down my throat, but it's something I don't want to have to hear.

I think the best response is to model the appropriate response, i.e., something in non-religious terms. Respond with the friendly farewell you would preferred to hear from her, like "Have a nice day." When she hears that you did not parrot her religiously-tinged response it might teach her something. Subtle, but it might work.

If I wanted to be snarky, I would respond with a religious type response from a religion that she does not adhere to, something like "Allah Akhbar." Invoking satanism seems to be a bit too aggressive and mean.