You have a point, but the person you're responding to makes a more important one - the colloquial definition of agnostic, in reference to religion, is a person who's not sure what they think about the existence of gods. When you call yourself an agnostic, that's what people typically understand by it.

That's the problem with surveys like this: the categories are political not philosophical.

It would be better to ask, "Does a deity feature amongst your considerations when making a decision?"

I take it that's what people are mainly interested in anyway.

If this question was asked alongside the others in these questionnaires I think you'd see a high percentage of non-atheist responders agreeing.

I am not making a point about the colloquial definition. The wikipedia article he linked disagrees with him too.

If that's the definition then it's useless as a distinguishing label since everyone on either side of faith can't know. If anyone could know, faith and belief wouldn't be necessary.

Many atheists and theists believe you can provide evidence one way or another. Most people are not agnostic.

There is a difference between saying you can prove something and saying you know something. Your own Wikipedia article disagrees with you.