I believe the burden of proof argument, as deployed by many atheists, is a bad argument, both ethically and philosophically.
The burden of proof argument claims that because theists have failed to adequately prove the existence of god, atheists need no further reason, evidence, or explanation for their own position of non-belief.
I do believe that extraordinary claims require extraordinary evidence. I do not deny that theists do have a larger burden in order to prove their claim. I simply do not think that this completely erases the need for an atheist to be able to support and defend their own position.
To begin with, ethically:
I believe that every person should be able to articulate why they do or do not hold particular beliefs (or, at the very least, beliefs that they spend time debating.) To me, this is an integrity thing. I can't imagine simply rejecting something, especially something that is widely held to be true-- whether it be evolution, or photosynthesis, or the existence of god-- without having an understanding of why I don't accept it.
Next, philosophically:
It seems to me that the burden-of-proof argument has been misused, or at least, not very well thought out.
Some background: The burden of proof is historically placed on the person making a positive claim. Thus, theists certainly have a burden of proof, as they claim that gods do in fact exist.
Many atheists have gotten around their own burden of proof by claiming to merely have a "lack of belief" in the existence of gods. They are not making a claim themselves; they are merely refusing to accept the claim of another.
Or are they?
The argumentation often goes like this: Theists have not met their burden of proof, therefore, I need no reason to not believe in the existence of gods.
Seems reasonable on the face of it, no? And it has been a convincing one, at least, to many atheists.
But look more closely. The atheist is making a claim: The claim that theists have not met their burden of proof.
Who decides this? There is no objective arbiter. Why should we, or the theist, accept the assertion that the burden of proof has not been met?
Is this not a claim that requires it's own proof?
So, how would you go about evidencing the claim that theists have not met their burden of proof?
You would need to go through various arguments made for the existence of gods and explain why they fail to provide sufficient evidence.
And yet, this is precisely what one would need to do in the first place, before burden of proof is even evoked: If a theists asks an atheist to support their position, the atheist could simply explain why the various arguments for the existence of gods has failed to convince her.
Which seems to me to make the whole burden of proof argumentation not only unethical, but useless as well.