Let us clear up Atheist Vs. Agnostic. These are not mutually exclusive terms. There are no atheists that exist that are also not agnostic. Being agnostic simply means that one acknowledges that it is impossible to prove a negative 100%. Being an atheist simply means one does not believe in theology. This next bit I read somewhere, but cannot remember where.
It is impossible to prove that unicorns do not exist, yet nobody seriously believes that they exist. To acknowledge that it is impossible to know, one would say they are agnostic about the existence of unicorns, but they also know there is no reason to believe that unicorns exist, thus one is also atheistic in regards to the existence of unicorns.
Although it is possible to be agnostic without being an atheist, any intelligent atheist (most are) is also agnostic. Anybody who claims to know with absolute certainty that there is no god is a fool, this however does not make god any more real than a unicorn, or for that matter a unicorn-leprechaun hybrid.
Atheists as far as I know are skeptics. Being an atheist in the USA is not something one does flippantly, very few are born into atheism. Unlike most religious people, an atheist at some point makes a conscious choice that they do not believe in religion.
Imagine, if you will, a prototypical balance, a plank of wood balanced on a wedge. Yet this is not an ordinary balance, this is a conceptual balance of evidence. This conceptual evidence balance is what rational people use in order to judge the accuracy of idea's and theories. Much of the time it is difficult to determine immediately which side of the balance is heavier, that is, which idea or theory has more evidence to it, however after research and a good amount of skepticism it becomes clear which side is heavier.
It must be noted that this sort of decision making is based on the assumption that it is rational to believe idea's with the most evidence for them, essentially the assumption is, it is rational to believe idea's that describe reality most accurately rather than ideas that describe reality less accurately.
People who use this sort of system to judge rationality are given the labels, rational, rationalist, or skeptics. Being a skeptic is synonymous with rationalist.
Now, getting back on subject, I have heard it said that atheists are just as close minded as theists. This is a gigantic lie.
Atheists, as mentioned above are mainly composed of skeptics, or rationalists who weigh evidence in order to make a decision about belief. These peoples beliefs are not set in stone, and change according to evidence. The fact of the matter is, there is overwhelming amounts of evidence that contradict the idea of a god in any sort of religious sense what-so-ever, and absolutely 0 evidence in favor of there being a god.
However every atheist I know would convert to any particular religion if there were more evidence of it being correct than of it not being correct.
There are exactly 0 theists that would do the same, simply because, any theist, if they used a rational system to evaluate evidence would come to the same conclusion as anybody who has ever looked objectively upon religion, and would realize it was all a scam.
The only reason a person would say an atheist is close minded is simply out of frustration that a skeptic cannot be swayed by stories like "I was personally touched by god" or any of that anecdotal evidence. These sorts of things are called spiritual experiences, and everybody, regardless of religion (or lack there of) have them. Atheists who do not believe in soul or "free will" have these sorts of profound experiences too.