There's a really long and recent thread on that around here somewhere. Short answer, I think "No thank you" would be a very rude and mean-spirited response. Saying nothing is better than that. But, simply saying "thanks" works for your fellow human being who really is not proselytizing in that situation. JMO.

I usually say gesundheit or bless you. I don't have a problem with anyone saying God bless you as I know it comes from a good place. They believe and I don't and as long as I'm respected I will respect. If someone is wishing me well or thinking of me and expresses it through their faith it's fine with me. I only have a problem if they try to force their faith on me.

Being rude is always a wrong thing to do.

The word bless , means to make happy . I can't be angry at someone wishing happiness on me , even it it's by an entity I don't believe in. I just say thank you , and move on .

Not an issue for me.
sneeze
"bless you."
sneeze
bless you
sneeze
"SHAADDAAP!!!"
Perfectly reasonable.

I just say bless you. I see it as being polite and to trivial too worry about...but I have thought about it.

I just smile & thank them. It's just them trying to be conventionally polite & not worth a potentially negative conversation.

I'll actually say it myself (just a simple 'bless you' sans a deity statement) to others for the same reason.

Much like if someone wishes me a Merry Christmas,... it's not innately offensive or aggressive from most people.

Saying, "bless you" lost it's religious significance very, very long ago. The superstition was that sneezing gave the devil an opportunity to enter the sneezer's body, so blessing them was protection against demonic possession. Today it's more a social convention than a protection against evil; a polite gesture more than anything else, therefore if someone says it to me I simply thank them for the acknowledgement. It costs nothing and avoids unnecessary conflict.

Gesundheit.

It was borrowed from German, where it literally means "health"; it was formed by a combination of gesund ("healthy" ) and -heit ("-hood" ). Wishing a person good health when they sneezed was traditionally believed to forestall the illness that a sneeze often portends.

I avoid participating in that ridiculous medieval superstition. No one's heart stops when they sneeze. There are no demons to take over the un-stopped heart of the sneezer.

If I feel like I'll suffer socially for not having the "good manners" to perpetuate this farce when someone else sneezes, I'll say "Gesundheit": "good health."

If I get a "God bless you" to my sneeze, I'll acknowledge it as minimally and wordlessly as possible. It's just considered manners these days, and I don't want to be seen as rude.

I have always said "sneeze you", and passed that on to my kids; as socially there are common norms that you HAVE to say something, so i picked the most secular thing I could think of. As for someone else saying it, I think the sentiment is completely unnecessary, but like a sneeze, it's somewhat involuntary in most cultures.

When someone else sneezes I either say, "gesundheit" or "spread your damned germs somewhere else." It all depends on who sneezed.
When people say, God bless you." to me, I thank them. It's a conditioned response.

Lol. I've been told it's rude not to say bless you. I asked that person, even an atheist who doesn't believe in blessings? She didn't know how to respond, but I could tell by the look on her face that she wanted to say something she knew would be offensive. I enjoyed that moment.

I say nothing when someone sneezes, unless I have a kleenex and they need one. When someone says bless you to me, I say thanks. Their intention is good, and I take it that way.

I've been asked why I don't say it by people who don't know I'm an atheist, and I respond "I'm not superstitious"

Salud or gesundheit.

I doesn't matter to me what anyone says when I sneeze. Habits are habits and I have heard staunch atheists say, "Bless you."

I generally don’t acknowledge it.

I think that you have forced me to rethink that remark...I do it myself! But, it really does not express what I mean! I am wishing them, 'well,' but I think I will find another way to do that!

I usually just say thank you. I personally would feel rude if I said no thanks. I feel like they're conveying kindness so I respond in kind.

Gesundheit!

I say "Excuse me." Like you would say excuse me if you had to burp, or if you were talking to someone and needed to step away or turn your body to cough, you'd say "excuse me." So when I sneeze, I say excuse me.

Goes in tight or Cunts tight.

They are just trying to be nice, and it doesn't occur to everyone that would be offensive. Maybe pick a better battle?

It’s harmless, no need to meet it with harm.

Gadzutekike!

When someone says "God bless you", when you sneeze, or at most any other time, they are just being polite as they were taught. You can safely bet that they have no malicious intent so why become a black-eye on agnostics by saying anything other than: Thank you very much.

I give them two free "bless you's." If they sneeze a third time, I'll spot them a "bless you," but warn them that I only have so many bless yous and then I'm out, so I don't want to spend them all in one place.