Tattoo discrimination in UK?

So today, for the first time in ten years, I received a rude comment about my tattoos in UK.

A female came out of nowhere next to my face on the bus to say that my middle finger tattoo is satanic (pentagram). It took me some time to understand what she said because she had a thick Eastern European accent, but she repeated herself.

I was taken aback, because how the fuck did she even manage to see it from where she was originally sitting?
And also, who the fuck does that?

I responded that it's not satanic and then got off the bus. She kept on saying that's how she knows the symbol, as part of satanic imagery. As we were walking away from the bus I was telling my partner 'who the fuck does that!' -in regards to the rude woman, and then she approached me again, to say I should have had a cross (!) tattooed instead.

I told her that since I'm an Atheist there's no point in me getting a cross tattoo and kept on walking noticeably irritated.

Usually, I respond quite aggressively to these kind of unsolicited comments, but it's always in Greece this happens to me, so I was shocked to have someone make such an anachronistic and rude comment in London.
Even more surprising was that the woman was no more than 40/45, so a young person.

I get my tattoos for me, they're not public property to be commented on. People need to mind their own business.