First off, Atheism or Theism is a statement of what you believe or don't believe. An Atheist can be Gnostic or Agnostic, sure or not sure.
I think you are referring to the fact that the claim: "there is no God" is unscientific and I would agree with you. But most Atheist are not Gnostic, they are Agnostic. A belief can not be "wrong" in the same sense as a fact. If there are no aliens, the statement; "there are aliens" would be wrong, but; "I believe in aliens but I don't know if they exists" would not be wrong. Therefor any Agnostic position can not be "wrong" since it means you don't know, this is true for both Agnostic Theists, Desists, Atheists, and all other belief systems.
It is not unscientific because It does not deal with science.
"What science do you feel Supports the non existence of God" Predictably The Atheist has responded with "There is no Evidence or Proof of God & Science requires empirical Evidence."
That is just shifting around the burden of proof... There is no proof of Gods none existence, and how could there be? Because there is no: "Evidence or Proof of God with Science by empirical Evidence."
And shifting around the burden of proof is something Theists and Atheists love doing...
Usually the Atheist would say: "you claim there is a man in the sky, so you prove that it is true"
The funny thing is that if the Theist is Agnostic and the Atheist is Gnostic, the Atheist would have the burden of proof. And vice versa.
Since this is a fundamental flaw in your premise your understanding and reasoning is not correct. I don't blame you thou, most people lack a good understanding of what they are talking about when it comes to this area, read all the definitions to get a better understanding on Wikipedia.
Cheers!