I wonder how much it would effect my business if I got anti theist tattoos. Considering I do a lot of religious tattoos. Lol
You're a tattoo artist?
You know your market better than me (a software developer with exactly zero tattoos) but I would imagine it's a little more ... edgy ... than most. All the skulls and ironic declarations and so forth. How would some atheist sentiments be out of place in that mix? I'd be inclined to go for it.
But you might ask a few of your customers who you've done religious work if they'd find it offensive. I can't see how they would with all the goth / LGBTQ / hedonistic themes that you probably already accommodate for other customers. But if anyone can figure out a way to be offended, it's a Christian. Your best hope is probably that most Christians who'd come to see you are probably pretty eclectic to begin with. A true fundamentalist would probably not be caught dead with a permanent tat, and they'd be the ones most likely to take umbrage to atheist themes.
Most of my clients know my stance on religion. I'm not shy about my none beliefs and my dislike of religion.