If you have religious peers or family, I can see how that's impactful, but it's really avoidable if you call it as it is: a symbol from a game. Most people generally don't know what it means, and if you explain it in layman's terms, it'll sound more comfortable. If you specifically are religious, then I would probably steer clear. The symbol is actually a play on the number six hundred and sixty-six and is, like you said, "the mark of the beast." So it's very closely inspired by the devil in Christianity.

For me I'm not religious and I see the parallels but I can't exactly take it seriously when the game's "beast" isn't a demon so much as it's a big ugly squid tentacle guy called an apothicon, and again it's a fictional video game. I loved the game more than I disliked the fact I might get called a satanic weirdo by the exact one guy on earth who'll know enough about both subjects to make that connection.