A reader writes:
Your atheist readers make the classic move of pretending to be the referee when in fact they are just another player on the field. They are treating it as an intellectual puzzle rather than what it actually is for every last of us: a lived commitment. This is why the term "Atheist" itself is so misleading. You're an atheist, fine. I'm an A-Vishnuist, and an A-Buddhist, and an A-Teapotist. Telling me what you don't believe tells me very little, but it's a really cool way to get into the conversation in such a way that everyone has to defend their positions except you -- you get to attack.
This would be valid were this merely an intellectual exercise. There you can usefully indulge the distinctly modern prejudice that doubt is more reasonable than belief. But you can no more avoid making a positive choice about the source of meaning in your life and the universe than you can avoid living in some country. You can talk about which country is best to live in, but the atheist pretends you can live in no country at all.
You gotta live somewhere, and you gotta believe in something, because your beliefs are being expressed every day in how you live your life. Atheists should be forced to articulate their positive position (say, secular humanism) as price of admission to the conversation. So when your reader wants to "put the burden of proof on the one making a specific, positive claim," I simply point out that living your life is a specific, positive claim, and thus everyone has to bear the burden of proof equally.