Get thee to a dictionary!
Ag-nos-tic: Without knowledge.
A-the-ist: not believing in any God or deity.
Examples:
Hard Atheist: There is no God, and there is no evidence to back up the claims to a God. We know for a fact there is no God, because there is no evidence (every few people are Hard Atheists). This is a non-believer with knowledge.
Agnostic Atheist, or "Weak Atheist": No physical proof means no God. However, absence of evidence does not mean evidence is absent. It's on you, who claims there is a God, to prove it. Until then, I do not believe, but I will admit that I do not know, either. Note the "I have no knowledge" part - that's the agnostic element, as agnostic means "without knowledge." It's a non-believer without knowledge.
Agnostic Deist: I believe in an unknowable God. There is no solid evidence to back the existence up, but I believe anyway. Note: this is believer without knowledge.
Theist: I believe in a God who plays an active role in our lives. I don't care that there isn't any evidence to back him up, I know in my heart of hearts that he exists and that's all that matters to me. This is a believer with knowledge.
Fundamentalist (Acephalic Theist): Responds to all of the above with: "There are people who don't believe like I do?! STOP PERSECUTING MEEEEEE!!! WWWAAAAAAAHHHH!!! From "a-" meaning, without, and "cephalus," meaning "head." Literally, believer without a head, more metaphorically, believer without a brain.
There, I hope that clears it up for you.