So, there you are, a scientist, impressed by the anti-religious fervor of the likes of Dawkins, believing that science can do away with God. You’re an atheist, in the sense that you believe there is no God, and that science licenses this conclusion.
But then, you’re also irrational. If you think God is outside the realm of the testable, science does not give you reason to believe anything about a potential God: neither that he exists nor that he doesn’t. If you believe God is in the realm of the empirical, science shows you a lack of evidence (which, as the famous saying goes, is not evidence of absence) and again leaves you without any reason to believe anything about God one way or the other.
In the current situation, therefore, you cannot both be rational and an atheist. The perfect scientist is agnostic.