Thanks to everyone for the responses! I learned a few new words through these answers. I was always under the impression that Gesundeit translated into "God bless you", but I looked it up and saw that it means "good health". I still don't like that sneezing is the only condition we acknowledge (leaving out coughs and hiccups), as that is based on superstition.

No. I may ask if they are alright if its a sneezing fit, but never say "bless you".

I often say pointedly silent in protest to the antiquated saying. There are some countries where people don't say anything at all

I don't say bless you, I say "Prosit". which is a swedish term used specifically when someone sneezes. nothing religious about it.

I do but by habit and that's how ingrained religion is in society. I also say for god's sake and Christ and even Jesus.

I say Gazunloose

If I'm moved to say anything at all it will be:

Salud

or

Gesundheit

I usually ignore it. I don't say anything when someone coughs, hiccups, or passes gas, so I'm unsure why sneezing earned itself such a revered place among bodily functions. (I've heard the story that it's because the heart stops when someone sneezes, but I don't believe there was a way hundreds of years ago to test that — if it's even true that it happens.)

I say Geshundheit, which wishes them good health.

It is literally taken years to break my self from this habit

No. I ask them if they’re ok?

"Curse you" seems too insensitive while "Get the hell away from me" implies a belief in something, therefore it's religious.

Yep. It comes from a long time ago when folks believed that when you sneezed, the Devil could get past your defences. I'm just trying to help my Believer friends and family avoid the potholes of life. They're having enogh trouble navigating the poisoned world their fellow Christian nut jobs are creating!

I've gotten used to the awkward silence.

I do, but for lack of better expression, I leave out the thing part, I wish there was a better translation from Albanian or Greek where the literal translation would be health or to your health...

I say it when someone sneezes. A 50 year old habit is hard to break, but I absolutely hate it when someone says "have a blessed day".

I do, I don't see blessing as any more than wishing them well, no god needed or implied.

I do say "Bless you", leaving off the thing word. Think it is just polite.

I do, but mostly out of habit.