I hate religion as much as the next person and one can argue about the number of deaths that religion has caused, but a religious person attending a convention is unlikely to directly cause other convention goers to die during the convention. Unless armed with weapon such as a gun. And if they suddenly start preaching and converting you can escort them safely off the premises.

So potential is good enough justification?

Anyone can carry a poison or a pathogen or simply be highly trained and know a lot, no need to carry anything, or even be obviously muscular.

I suppose it must be reasonable to bar anyone who knows how to lock doors and start fires, or mix cleaning supplies. Assume we had an equivant way to scan for it like a metal detector or a frisking.

> So potential is good enough justification?

If you disagree that potential is a good enough justification, would you agree that private citizens should be able to own nuclear bombs? If not, why? If you do think citizens owning nuclear bombs is reasonable, I don't think we will find common ground.

> Anyone can carry a poison or a pathogen or simply be highly trained and know a lot, no need to carry anything, or even be obviously muscular.

Try attending a conference openly carrying a bucket of arsenic or a bottle of anthrax. Or just a jerrycan with gasoline and some matches. Or wearing a bomb vest and wielding a machete. I like to imagine you will be sent away. It's not like guns are unfairly targeted here.

When those other methods of murdering people are as common in the death-statistics as firearms (such as the "killing spree by a muscular martial artist" one you propose), perhaps we should worry about them more. But they are not, so banning guns is the most logical step to increase safety.

No matter how many times you remove the top of any list, there is still a top of the list. It accomplishes nothing.

True, carrying a pail of nerve gas, or even merely gasoline, somewhere out of context will be prevented generally for it's mere potential, but there are several things about that:

It was a remarkable out of context event, not someone merely existing as they do all day every day, where their weapon is a part of them like their wallet or their knowledge.

You don't have to carry anything large that is detectable without a rather invasive search which you cannot perform outside of maybe North Korea.

You don't have to carry anything at all. The danger is all in the will and abilities of any individual.

Saying nuclear bomb is a form of Godwin's law. Merely saying it at all exposes that one is not arguing from meaningful thought or data but pure hyperbole and emotion.