@igm,
Logic is a means by which we arrive at a conclusion. We wouldn't get anywhere if we did not draw conclusions from logic.
Electrical theory is still a theory after all.
Atheists are not any more illogical than agnostics.
As in the case of pure logic, we simply conclude that you can always add one more, and get on with our business.
The atheist concludes that a creator is not necessary to the existence of the universe, and gets on with the business of life.
There is nothing, whatsoever, illogical about that.