Summary, there are three classes:
I believe in god. _ Theist.
I don't believe in god. _ Atheist.
What's a god? _ Agnostic.
And those titles aren't etched in stone, you are allowed to change your mind whenever you need to. You can be a theist and say "I think god exists, but I'm not sure." Likewise you can be an atheist and say "I don't think god exists but I'm not sure
Why don't you use an english dictionary? Agnostic is not What's a god. Agnostic is you dont know whether there is a God or not.
If you use an english dictionary you cant be a theist and say, I think God exist, but I'm not sure. When you are not sure you are an agnostic when you are sure there is a God you are a theist. When you are sure there is no God you are an Atheist. If you do not use an English dictionary its all mumbo jumbo.
Go to dictionary dot.com. Agnostic is not "Whats a God." Agnostic is you don't know whether there is a God or not.
There are 3 posibilities positve, negative and neutral. Agnostic is neutral. Is english your native tounge?