I don’t think Christianity requires circumcising

It may have started that way, but nowadays it's normalized to the point where it's something most people just automatically do. Any harm to the person undergoing this is waved away and rationalized as "it will hurt for just a second and they won't remember it anyway".

After my brother-in-law had his boy, he proudly announced they were taking him to be circumcized. Taken aback, I asked him why - he's one of the most non-religious people I've ever known. I was just met by an empty stare, as if I were the weird one for asking. Sadly, at this point it might be more popular than the essential vaccines which are supposed to be administered at birth.