I would never ask that question because you put yourself in a no win situation. Also I really dislike when someone tries to push their beliefs on me so I figure they probably feel the same way. To me it is just a matter of mutual respect. The older I get the more picky I am in choosing my battles.

take a piece of paper put it on a table  an blow under it to make it move  and then say put paper on the table and have god make it move  If they say that's stupid . say no I showed you air by making the paper move. now have god do it. Or just point out how childness they are being

Well, not only can we feel air, we can capture it, measure it, experiment with it, use it, compress it, liquefy it, store it, transport it, cool it, hear it, weight it, see it (under the right conditions)... We get the idea. It is a physical thing. The measurable evidence of which is abundant. Ask them what "quality" of their god is measurable.

The response to a challenge can't be another challenge.

Well...

Oh oh!!! Tell them you don’t believe in air! See if their heads explode or something cool like that.

I just fart in their face.

Just blow on them. That's one demonstration of Air. Just because something can't be seen does not mean it isn't there, but it CAN still be DEMONSTRATED!

Well, when I tried holding their nose, and covering their mouth, I was informed by law enforcement that wasn't considered a valid science experiment.

Boom

Blow up a balloon.

I generally don't argue this. It is impossible to argue against faith with facts. If it is in a group of "believers" the singled out person trying to argue using facts is outvoted and comes off as a crazy person. Never have I seen this arguement won.

That is when I would fart, so they can smell it too.

Turn on a fan, or wave a paper one you just made.

It must be different in UK we don't have this saying .. I would just look at them like they were a complete Fucktard .. because they would be .. then I would likely sigh and walk off lol

I tell them, "Take a deep breath."

It's not a question I would ever ask. It's pointless to debate with someone who refuses to listen to reason or make evidence-based decisions. They'll just take it "on faith." Mmm hmm.

It's a doomed conversation from the start. You know there is no God so why would you challange someone to show you otherwise. Prostalitizing is for insecure zelots.

Don't get drawn in to those silly conversations.

Blow up a balloon and then deflate it.

Don't generally go out of my way to have discussions like that. They're going to believe what they want, me too.

I have lived my life quite happily without god, as have many others. Now as I place my hands around your throat, live without air.

Simple. I'd say that air is merely our name for the collection of gases which makes up our atmosphere, that we can analyse what gases make up "air", and that we can actually see these elements with scientific equipment. Moreover, our observations match precisely the hypotheses and theories developed over centuries regarding the nature of elements and what elements exist.

Tell them o.k. then fart