For some reason most theists and even some atheists seem to have trouble with the concepts of agnosticism versus atheism. In this article, I'm going to try to address the apparent confusion around these two terms. With any luck this will be a useful resource for theists and atheists alike.
The root of agnosticism is gnosis. According to Merriam-Webster's Online Dictionary gnosis is:
: esoteric knowledge of spiritual truth held by the ancient Gnostics to be essential to salvation
Therefore, to be agnostic is to be without this special knowledge. Again, according to Merriam-Webster's Online Dictionary agnostic is:
: a person who holds the view that any ultimate reality (as God) is unknown and probably unknowable; broadly : one who is not committed to believing in either the existence or the nonexistence of God or a god
The root of atheism is theos from which theism is derived. According to Merriam-Webster's Online Dictionary theism is:
: belief in the existence of a god or gods; specifically : belief in the existence of one God viewed as the creative source of the human race and the world who transcends yet is immanent in the worldThen an atheist is someone who does NOT believe in the existence of deities. From Merriam-Webster's Online Dictionary atheism is:
: a disbelief in the existence of deity
Most atheists will naturally fall into the agnostic camp. There being no verifiable, empirical evidence of deities means that one cannot know for certain about the actual existence of said deities. So while an atheist may not believe in the existence of any deities, without searching all space-time they cannot know for absolute certain that one does not exist. However, given the improbable likelihood of ever being able to perform such a search it is not necessary to do so in order to show that no deities exist. If there are deities in the Universe and they are not in anyway observable within the space we search then we can infer that they do not affect us and are as good as nonexistent. That said, given the complete lack of evidence of deities up to this point some atheists believe that such a lack of evidence is compelling enough evidence to positively conclude that there are no deities.
It is interesting to note that most theists are actually agnostics as well. They, much like atheists have no verifiable, empirical evidence of the existence of their particular or any other deities. While a theist may actually believe in the existence of a certain set of deities they cannot know for certain that any actually do exist. Theists that say they actually know that deities exist is either deluded or lying. Unfortunately for the theist making a positive claim, as no verifiable, empirical evidence of deities has yet been found, it falls on them to prove the existence of the deities they say exist.
Naturally, some theists object to this and claim that atheists that make a positive claim of the absence of deities also bear the burden of proof. However, this is not true. Given the fact that up to this date no deities have been found the Null Hypothesis is that there are no deities. As a result, the atheist making the positive claim is not really obligated to prove that deities don't exist because the view of these particular atheists are in line with the Null Hypothesis. Since the theist has, through making a positive claim, constructed an Alternative Hypothesis he or she now bears the burden of collecting the evidence and seeing which hypothesis is supported by this evidence.
Bear in mind that this does not get the atheists off "Scott Free". Should a theist actually find any verifiable, empirical evidence of the existence of deities and this evidence passes scrutiny then the Null Hypothesis may change and the atheists will now have to reevaluate their beliefs, or lack thereof as the case may be. However, until that happens atheists can rest assured that theists will spend a long time looking for the existence of their deities which started at the dawn of religion.