Believers, put yourself in my place.

[Homeless Nutter]

Perhaps, what is wrong too with defining atheism as lack of belief in God is to not define anything at all.

Perhaps what is wrong - is something with your way of thinking? Perhaps you were brainwashed into believing, that everyone has to pretend to know everything, the way religious people do? It's perfectly possible for an honest and intelligent person to admit not knowing sh*t, without making up invisible sky-daddies and such. And it's perfectly possible for such a person to reject - in the absence of evidence - empty claims made by goat-fondling, desert dwelling lunatics and frauds, long time ago. And that's atheism, my boy/girl(?).

For all -ism holds on to some affirmation and not merely describing some lack-ness. This is the first time that a term with -ism is defined with lacking. Are there any other definition which have defined the way new definition of atheism is defined?

What, you mean like - anarchism (rejection of government and laws), vegetarianism (rejection of meat), nihilism (rejection of pretty much everything)?... Do I need to go on or are you ready to admit you're being a dumb-ass?