There are a few things I tend to talk about more often, which may indicate a more common kind of question.

- You don’t need “evidence of absence” not to believe in something (then give examples by pointing to things the asker doesn’t believe in – in spite of no evidence to the contrary – including, for example, every other religion’s gods). I join them in their many disbeliefs in spite of not always having evidence to the contrary.

- Often quote Sagan’s “extraordinary claims require extraordinary evidence”, and point out that it’s the ultimate in extraordinary claims.

- I say I agree with their nonbelief in other people’s gods for that reason… but I also agree with the other fellow’s disbelief in theirs for the same reason.

- there’s usually some misconceptions about atheism to clear up – but often different onse each time. Common ones include nihilism, anger (though I point out that there’s no lack of things for atheists to be rightly cranky about), being angry with god (!), not wanting any rules, …

This sometimes gets people to shut up since they know they don’t believe in much of the bible either. Or they may argue this fact since they have never actually read the bible themselves. I’ve encountered people that the only thing they know is to have Jesus in your heart and that he died for our sins. Everything else comes from their pastor.

I got honest with myself and realized that I had never had anything that I would consider to be acknowledgement from god.

I got honest with myself and realized that I had been fooling myself.

I think the point that pushed me over the edge from deist to atheist, that I always include, was reading Stephen Hawking’s “Brief History of Time” and learning about evolution–when the gaps started shrinking, god just seemed so superfluous.
(The journey from fundie to deist was a lot more complicated, though, and so that story may or may not get emphasis)

That’s the phrasing I use for theists, but I said essentially the same thing in how I became an atheist, which I wrote for a general audience (including atheists).

Usually I don’t get an answer to that.