It is a natural, flat out instinctive reaction because it is deeply ingrained in our past. Someone sneezes, and no matter your beliefs you feel inclined to say something. "Bless you" or the German "gesundheit" perhaps.
There are several thoughts on it's origins of this phrase but they date back as far as AD 77. Yes nearly 2000 years ago!
Can someone tell me why we are holding on to this? It drives me crazy sometimes. Even people who aren't religious say it when this term was born out of catholicism. The only time you'll hear me say these words is because I don't want someone to feel insulted because I didn't say it.
Starting today I'm done. I won't be saying it anymore. It's yet another outdated piece of Catholic that we really need to just let go. Who is with me?