means no belief in a deity. None. It chafes me (and many others) that we are defined by the absence of a commonly championed delusion - the belief in a deity. It has been said before that no one would expect anyone to have to define themselves as an amormon, acatholic, amuslim, or, even, afairiest. Nevertheless, I suppose the prevailing delusion pushes us to distinguish ourselves from the pack by labeling ourselves as non-believers.
Agnosticism, on the other hand, is a word that truly is misinterpreted in a way that chafes me. It means that one simply admits that they have not and, likely, will never corner the market on understanding the absolute nature of reality (if such a thing even exists.) It does not - as a word - have anything to do with a god. In fact, belief in even the likelihood of a god is counter to an agnostic position. The idea that there might be a god (at least a god that resembles any one of the more popular of the 4,200 formal definitions) suggests that an absolute answer might well be found in some scripture or another.
Look at it this way: When asked to describe the mechanisms involved in the initiation of life on Earth, the most learned scientist studying the origins of life may well describe a number of possible scenarios - or even narrow it to one. But if you ask them if life may have arisen in a different manner; in all intellectual honesty, they would have to admit that they cannot be sure. They may be willing to presume that we may someday be reasonably certain of at least one way it happened - but there is always the possibility (even probability) that life originated in a variety of places and by a number of mechanisms. In this, the scientist (more than likely, an atheist) is agnostic about the precise process by which life emerged on this planet even as they learn more and more about how it, very likely, did originate.
Scientists are, at the end of the day, usually not only comfortable with admitting that they do not yet know something, but are spurred on by the mysteries yet available to pursue. Basically, a scientist is more comfortable with admitting a great deal of ignorance than simply making up an answer whenever they don't actually have one.
Thus - agnostic atheist is not only not an oxymoron - it is the most reasonable position an atheist can take. Basically, an atheist can say that one reason they do not believe in a god is that, while they don't think that any version of god has anything to do with an accurate description of the true nature of life, the universe, and everything; they are happy to admit that they do not know what that answer actually is on an absolute level.
On the other hand, the minute a person has total faith in a deity - especially in a specific deity as described in some book somewhere - they have abandoned the notion that there is any remaining doubt as to what is going on. Sure, the Catholics can sidestep inconsistencies of their faith with their cute little 'it's a mystery' dodgeology (my word - use it freely.) Nevertheless, the vast majority of theists including Catholics basically claim that they have cornered the market on the absolute truth - at least to the extent that they have achieved eternal bliss while all others are doomed to eternal torture. Therefore, agnostic theist is an oxymoron. The closest a theist will get to agnosticism will be; 'I am in possession of the most sacred truth even if I can't explain it - even to myself.' (Pardon the potential strawman there - but I stand by that statement as a reasonably accurate portrayal of every theist I have ever met who claimed to have no doubt in their faith.)
Perhaps it is possible that there are agnostics who think a god is one possibility - unlike atheists. But I find it very difficult to refer to that position as an actual belief let alone a faith. Personally, I think that that position is one that is simply a result of either vestigial elements of a former faith, or some other cultural pressure to avoid seeing the majority of the human race as delusional on this point.
It is fairly easy for most to admit that the vast majority of human beings a thousand years ago were delusional on some aspects of their world view. Yet, somehow, many hope that a majority view - by now - might have a chance of having transcended pure delusion. Alas, this is but a feeble and unfounded hope. We all - atheists included - hold some things to be true that will turn out not to be - whether we discover or admit these fallacies in our lifetimes or not.
I am an atheist. I am certain that, whatever is happening, no god ever described by human beings ever existed. Nevertheless, I am happily agnostic about what is actually happening at any level of reality to an absolute degree. I say 'happily' because I love a good mystery. Heaven would be hell to me partly because there would be no more mystery, no more room for advancement, no more reason for aspiration, curiosity, exploration, or progress. For me, agnosticism is an intrinsic element of my atheism.
Not knowing everything is why I get out of bed in the morning.