Being an atheist in Texas, I change my lingo up and say gods below and bullshit like that. Mostly to get a point across. And to make small minded people to piss off when they knock on my door on Saturday mornings.
Thank the tiny gods is one of my favorites on thr positive side. If you can also wrangle jesus fucking christ into the conversation you get extra points.
I'm pretty comfortable with it since there's no god to be afraid of. It's the people who believe in god that have to avoid pissing him off by not having a good enough reason to call him, or something.
If anything, it's a little bit transgressive and that's fun.
I'm an atheist but saying things like oh my god or calling for Christ or his mother is so ingrained in my mother language that it's just a meaningless jerk reflex sound... Like saying ow, or sneezing...
I was at the gas station the other day and both cash registers opened up at the same time. The guy in front of me isn't even buying anything. I hear him ask the cashier what she thinks of Jesus Christ. I look over at him with a wtf? Look. The cashier says "well he's out savior" and he says "good, good" hands her a pamphlet and I shake my head saying "Jesus fucking Christ" as Jesus boy fucks off and heads out the door. No reason to be there whatsoever. The cashier I was at laughs and says "I was JUST telling her not 3 minutes ago that i can't deal with any more crazy today." Why do these people do this shit? Keep it to yourself. I'm gonna lose my shit on someone someday forcing their mental health disorders on others one of these days. I haven't yet, but it's bound to happen.
JFC is what I say when I'm truly exasperated. I have no issue with using either term when surprised or angry or otherwise.
What I'm very careful about is saying "thank goodness." Never thank god. There is no god to thank. And if there was, fuck him for making such a terrible world.