Myth:
Atheists are convinced that there is nothing that humans cannot know, but there is no way to know this. This is faith at best, but is really an example of arrogance and human conceit.
Response:
Atheists are frequently accused of being arrogant for thinking that they know too much. Sometimes they are accused of thinking they can know God doesn't exist (but it's OK for theists to say they know God does exist). Other times they are accused of presuming to know more than intelligent theists who believe in God (but it's OK for theists to presume to know more than intelligent atheists). Here, we have the accusation that atheists think nothing is beyond human knowledge.
These accusations are almost always accompanied by a promotion of ignorance: it isn't just that atheists are wrong for presuming to know things they can't, but they are also wrong for not realizing that it's good to not know things. It's a sign of humility to not only accept that there are some things you cannot know, but also to accept that there are things which are necessarily beyond any human comprehension. It's good to be ignorant and to be happy in our ignorance. Atheists who refuse to accept this are conceited because they are claiming to have the power and/or knowledge of a god — if there is no knowledge that can be denied to human beings, then there is no power or action that can be denied to human beings.
The first thing to note about this myth is that the conclusion does not follow from the premises. Religious theists who want to attribute this sort arrogance to atheists cannot do so on the basis of the idea that atheists think humans can know anything. The presence of knowledge does not in any way automatically justify the power or authority to do something in particular. No matter how much a human being knows, we cannot conclude that they must also think they can do as they will.
The second thing to note about this myth is how rooted it is in Christian mythology about the evil nature of knowledge. It may not be unreasonable to suggest that the limited nature of human beings may necessarily place some ideas outside our sphere of knowledge, but without Christian myths lurking in the background there is no reason to ascribe negative moral qualities to the desire to know more or the assumption that there is nothing that cannot be known. It is in fact one of the great crimes of Christianity to place arbitrary, theological limits on the quest for more knowledge and understanding.
Each attempt to assert that atheists are wrong for thinking that they can know everything will proceed in slightly different ways, but there is a common pattern of citing examples of things we don't know now as justification. The nature of consciousness and process of human thinking is currently beyond our knowledge, therefore it's wrong to assert that nothing is beyond our knowledge. The origin of the universe is currently beyond our knowledge, therefore it's wrong to assert that nothing is beyond our knowledge. The behavior of subatomic particles is currently beyond our knowledge, therefore it's wrong to assert that nothing is beyond our knowledge.
The argument is rarely stated in such clear terms, but this is what they always reduce to. The reason why the argument is never stated so simply is because once done, it becomes clear just how wrong it is. The premise that we don't know something now cannot even justify the conclusion that we will never know it, much less the much stronger and broader conclusion that there are other things which we will never know. Maybe it's true that there are things which no human being will ever be able to know, but the truth of this conclusion cannot be founded on the premises being offered as part of this myth.
Indeed, there is no argument which can justify such a strong conclusion. The most we can reasonably conclude is that there might be things we'll never figure out, and that's only because as limited beings we are imperfect and prone to error. This conclusion is much more limited than the one which some religious theists want to use, however, and makes it more difficult to attack atheists as being arrogant, smug, or conceited. It doesn't sound as good to merely say that atheists are conceited because they might be mistaken.
And what of the claim itself — do atheists believe that there is nothing beyond human knowledge? This is not a position which follows automatically or necessarily from atheism itself. Anyone who claims that this is true of all atheists clearly doesn't know enough about atheism to be offering an informed opinion about either atheism itself or atheists generally. Whatever they have to say, it should be treated very skeptically.
Atheists can and will take a variety of positions on the question of whether there is anything that might be beyond human comprehension. Some may deny this. Some will agree with it. In my experience, though, most take a much more limited position and accept that while there may be things we can never know, there is no reason to assume that this is necessarily the case and we certainly shouldn't adopt it as part of our quest for knowledge.
Good science doesn't start out by assuming that the answers to a question won't be found — it proceeds by assuming that if the questions are right, then the answers will be discovered eventually. Perhaps this assumption will be proven wrong some day, but it hasn't been proven wrong yet. In the quest for knowledge, it makes absolutely no sense to start out by assuming that you'll fail.
It's more characteristic of religion to assume that there are "mysteries" which are beyond human comprehension and which we must simply accept. It's more characteristic of science to assume that anything that's part of the natural world can and will be understood if we simply invest enough time and effort. It's no coincidence that science has produced far more knowledge and understanding about our universe in the past couple of hundred years than religion has managed over many millennia.
