John Loftis, at his blog Debunking Christianity, lists ten objections, concepts, or topics that seem to be raised most often by atheists in debates with theists. Here's the fourth (my response to the earlier objections can be found by scrolling down the page):
4. An atheist is under no obligation to take your theology seriously. It's your belief, you need to justify it in secular terms. Just as a Hindu or a Scientologist would.
It's not clear what is meant by this. If it means that theistic belief needs to be justified in non-theistic terms that's clearly a case of requiring the impossible.
If it means that the theist should build a bridge to the atheist by employing resources in the conversation that draw on current philosophical, historical, and scientific knowledge that both interlocutors accept then the claim is unexceptional.
I'd like to suggest, though, that in the dialogue between theists and atheists it's the atheist who more often fails to justify his belief. Theists have made numerous sound arguments to support their conviction that God exists, including the argument that belief in God is properly basic and does not require evidential justification, but atheists have found it very difficult to come up with any cogent argument to justify their disbelief other than to insert their fingers into their ears and pretend the theist hasn't made a cogent case.
The atheist certainly has no good argument, except superficially the argument from suffering, to support his claim that God does not exist (lest anyone object that atheists don't actually make the strong claim that God doesn't exist, I refer them to chapter 12 in Alex Rosenberg's Atheist Guide to Reality.). Thus, #4 applies a forteriori to the atheist.