Atheism is a religion

Apologists frequently assert that atheism is a religion. Whether this is true or not depends greatly on what definitions of atheism and religion are being used. The argument is most effectively made against strong atheism, in which positive assertions are made that no gods exist, but even in that case there are real problems with applying the label of religion to something that is explicitly denying a central belief of almost all religions. Further muddying the issue is the purely legal notion that, for the purposes of the First Amendment's free exercise clause, atheism should be considered a form of religion worthy of protection.

Apologetics
If you truly believe that there is no god, how is that different from believing that there is a god? Both are positions on a fundamentally religious question that must ultimately rest on faith. Therefore, atheism is just another form of religion.

Non-differentiating Definitions
Now that religion is based on groups of people, everything from baseball teams to people sitting in a waiting room, are now religions. Few would find the argument compelling: "Oranges are made of matter. Stars are made of matter. Therefore, oranges are kinds of stars." Whether something is made of matter is not what distinguishes a star from a non-star. Other non-distinguishing comparisons that commonly come up: While most religions do these things, they aren't religions because of these aspects - but rather by a set of attributes that distinguish it from other concepts, such as belief in supernatural events or beings.
 * Frequently, atheism is equated to religion by using non-differentiating definitions, meaning, aspects of a concept that do not distinguish the concept from others, are used for comparison. For example:
 * Religion is a group of people.
 * Atheists are a group of people.
 * Therefore, atheism is a religion.
 * Getting together in groups / socializing
 * Having a set of beliefs
 * Having tax-exempt status
 * Having a belief about gods
 * Voicing our concerns/opinions ("proselytizing" or "evangelizing")

Additional Counter-Apologetics

 * "If I'm not buying what you're selling, it doesn't mean I'm selling something else."


 * According to dictionary.com, the primary definition of religion is:
 * 1) a set of beliefs concerning the cause, nature, and purpose of the universe, esp. when considered as the creation of a superhuman agency or agencies, usually involving devotional and ritual observances, and often containing a moral code governing the conduct of human affairs.


 * There's a lot of wiggle room in those "especially"s and "usually"s. Does atheism (strong or not) consider the universe as a creation of superhuman agency? Of course not; just the opposite (in that atheists do not believe in such a superhuman agent in the first place).  Must atheism in all cases involve devotional and ritual observance?   No.   Must atheism in all cases prescribe a moral code?  No.  Of course, there are systems of morality that atheists would be comfortable calling their own (see the article on secular morality), but atheism in itself does not suggest which moral system one should follow.


 * More to the point, is atheism a set of beliefs concerning the cause, nature, and purpose of the universe? No.  Atheism is a lack of one specific belief, not a set of beliefs. Even strong atheism is simply a position on one particular issue: there is no god.  Thus, even assuming strong belief in this point, that doesn't say anything at all about the actual cause, nature or purpose of the universe, except in the negative ("it's not God").


 * People who think that atheists are all of one mind about the nature of the universe need only consider the beliefs of Raelians to see this is not so.


 * Some people claim that atheism is a religion based on later definitions of the word, such as:
 * something one believes in and follows devotedly; a point or matter of ethics or conscience: [for example] to make a religion of fighting prejudice.
 * Technically, atheism could be considered a religion in this sense, but this wanders very far from what theists imply when they call atheism a religion, and can thus be considered equivocation. As the entry itself mentions, under this definition "fighting prejudice" is a religion.  If this is true, then so are capitalism, football, and Star Trek.  It is surely not much of an insult to be included under such a broad definition. (On the other hand, many religious people would likely be insulted if this were taken to be the only meaning of the term when applied to their own religion!) Atheism would be a religion in the same sense that golf is a religion but not in the sense that Catholicism is a religion.


 * If atheism is a religion, not collecting stamps is a hobby.
 * If atheism is a religion, bald is a hair color.
 * If atheism is a religion, being healthy is a disease.
 * Tu quoque! This argument exists to defend religion by claiming that atheists fall into the same category. This serves to derail the argument and prevents focusing on the lack of evidence for the religion. Beyond shifting the burden of proof, the argument serves as a non-sequitur.

Dissolving the Question
Words are hidden inferences. By calling atheism a religion, the person wants to come to some conclusion using a syllogism such as:
 * 1) Religions force people to wear silly hats.
 * 2) Atheism is a religion.
 * 3) Therefore, atheism forces people to wear silly hats.

These syllogisms don't work. Humans have ten fingers; but if I lose a finger in a chainsaw accident, I am still a human.

Since you are talking about a very specific instance, there's no need to go through the generalization for any specific questions about atheism. However, this might have come up when the atheist in the conversation made a point about religion. In this case, talk about the specific aspect of religions that fits your argument, and stop using the word 'religion' (or synonyms). For example, when saying that religion is harmful, you might want to switch to saying that dogmatic movements are harmful -- an argument that might exclude a small number of religions and include some political movements used in dictatorships.