Would you consider it offensive if an atheist …

Would you consider it offensive if an atheist with a deep fascination and respect for Norse paganism got a rune tattooed?

nope, not at all; one of my coworkers when I was working at maccas had Ingwaz tattooed behind her ear because she’d chosen it at random when she was drunk one time and that didn’t bother me, I was just excited to see the rune..! haha

I do find it amusing when people use Norse symbology they clearly don’t understand, but even then I still don’t find it offensive (not including fascist misappropriation, ofc). And from how you’ve described yourself, that’s not you anyway.

I say go for it if you want to 🙂 though do be aware that it’s possible some people might, unfortunately, associate your tattoo with racist intent (due to the aforementioned fascist misappropriation – it’s a bummer, i know; fascists are the worst)