In political discourse (if such a thing still exists) one often hears various religious groups claim that atheism is just another religion and therefore the removal of God from the public square is the same as instituting yet another religion, atheism. Though I understand this sentiment, the fact is atheism is anything but a religion.
A religion requires some form of systematic thought concerning a superhuman controlling power complete with observable boundaries in terms of behavior and ritual. The belief in a God is typical in religion but not necessary, and this is where the confusion begins for some people. Just because religion can be Godless does not mean that atheism is therefore a religion.
Far from being a religion, atheism, as a stand-alone term, is not even a worldview, its not even an argument. Atheism is simply the lack of belief in God(s). Atheism is to a worldview what a ball is to a sport. To say that atheism is a religion is like saying “This ball is a sport.” Some sports use balls, but there is no sport called ball. Likewise, atheism is only an element found in certain worldviews, but does not constitute a worldview by itself. Without a worldview, a philosophy, a set of logical inferences based on evidences, without some form of coherent argument, all one has is an assertion.
(As a side note, there is an interesting conclusion from what has been said here. What is true for atheism is also true for theism: theism, as a stand-alone term, simply denotes belief in God(s). By itself theism is not a religion, hence to claim that having belief in God(s) in the public square is the equivalent of government instituting a religion is patently illogical.)