Is atheism a belief?

[Whateverist]

You've misattributed these quotes to the wrong member.  I'm the one you're answering here.

Knowledge is usually defined as justified true belief. 
Are you seriously claiming all your beliefs are knowledge based by this definition?

No. I use the dictionary definition.

You can go with a more informal definition but then you'll just be begging the question "what makes you so sure you know that?"

So you're basically saying "I go with what I know".  Does that mean you're not claiming that what you 'know' should count as a fact for anyone else, that you have no justification for what you think is true you could reasonably expect to convince anyone else?  If that is what you mean, why call it knowledge?  Isn't it really just what you happen to believe?

You seem to be having trouble with the idea that a person can reasonably check both boxes: 
no, I hold no belief in any god; and no, I don't know if any gods actually exist

I didn't say that. I reject the claim that some people make which is agnosticism automatically equals atheism 

I don't know anyone who thinks agnosticism implies atheism.  Every right thinking theist should also be an agnostic.  However fewer theists get to that point, though they do exist and are not rare if you know where to look.

I do not claim that agnosticism implies atheism, I just happen to be both myself.  Are you saying then that you are an agnostic theist?  If so, much respect.  There is nothing wrong with that.