Yes it is.  And it is not mutually exclusive with atheism.

Agnosticism is from the greek word gnostic meaning knowledge.  It refers to what we claim to know.  I am agnostic because I do not claim to know there is no god (although that depends on the specific god being proposed.)

Atheism refers to belief.  Whether you believe in a god (theist) or not (atheist).  I do not believe in a god, so I consider myself an atheist.

I would accept either label.  However, for the sake of clear communication I prefer to use atheist.  Because, I am really really really confident that no god that has been proposed actually exists.  I would say my certainty is above 99%.  And I think atheist better conveys that belief.

This is what we mean by atheist.  And just like I'm not going to try to define what you mean by Catholic, I'd appreciate it if you do not attempt to straw man me by defining what I mean by atheist.  Way more interested in your response to my other post at any rate.

Again, most people didn't even respond to my arguments, so I consider them standing.

Most of the arguments are so absurd that nobody wants to legitimize them by responding to them. 

That's why these people aren't philosophers.

People who self-define as agnostic usually don't consider themselves theïsts or atheïsts.

The problem with this response is that it defaults to the idea that all arguments are valid when that is not the case at all. Many arguments are absurd and should not have a place at the table of discussion. Many of your arguments are cheeky little thought experiments but have little to no place in an actual discussion about the nature of the universe. 

May I inform you that the Wiener Kreiss doesn't exist anymore? Metaphysical reasoning is taken seriously in academics? If you really think you know better, write a book about it and challange some other philosophers.

Well, then I would disagree with their usage of the word, and if I were talking to one of them, we'd have to each clarify what we meant and come to an understanding.  I would suggest that their usage of the word leads to confusion, and that we would be better off agreeing with the way I use it for the sake of clarity.  But that's kind of irrelevant to this discussion.

 I have defined what I mean by it, and I can give you plenty of sources that define it in this way.  So, that's the definition I'm using, and as far as I can tell, the way most if not all of the other atheists in this topic have been using it.  As long as everyone in the conversation understands the meaning, that's all that is required.

With that out of the way, I'd like to understand how your argument is valid when the conclusion does not follow the premises.

If you truly think you know better, then why don't you write a book proving your little thought experiments belong anywhere outside of a philosophy classroom.