The burden of proof is definitely upon such atheists to give a positive argument with verifiable evidence that their extraordinary claim is correct.
Where is the scientific experiment conducted by atheists that definitively proved that "There is no God"? How was the experiment conducted? Which science journal was it published in and who were the researchers? How did they define the God whom they state doesn't exist? What is the exactly measured probability and what calculation was used to get that probability?
Note that the above claim puts to rest the incorrect notion that atheists never make claims about God. The advertisement is a direct claim.
2. an assertion of something as true, real, or factual
Collins English Dictionary – Complete and Unabridged © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003
I demand evidence for the extraordinary atheist claim that "There is no God". The absolutist claim that "There is no God" is a dogma by dictionary definition.
dog·ma (dôgm, dg-)
n. pl. dog·mas or dog·ma·ta (-m-t)
2. An authoritative principle, belief, or statement of ideas or opinion, especially one considered to be absolutely true.
3. A principle or belief or a group of them.
The American Heritage® Dictionary of the English Language, Fourth Edition copyright ©2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.
"He who asserts must prove." The burden of proof is upon the person who claims "There is no God."
Quoting Christopher Hitchens - "That which can be asserted without evidence, can be dismissed without evidence." If atheists cannot give positive evidence for their claims then their claims can be dismissed.
Why do the rules above not apply to atheist claims? Isn't a rejection of these rules for atheists a case of special pleading?
Atheist A accepts standard(s) S ["Extraordinary claims require extraordinary evidence." & "He who asserts must prove." ] and applies them to those who are not atheists in circumtance(s) C [Statements of belief and / or nonbelief]
Atheist A is in circumstance(s) C [Stating the extraordinary claim of nonbelief "There is no God"].
Therefore Atheist A is exempt from S.