Atheism is a religion, look up the word on dictionary.com.
Here is a hint:
something one believes in and follows devotedly; a point or matter of ethics or conscience
And that is where you are wrong. Atheism is DISBELIEF. Not belief.
But since we are playing this game.. let us continue...
–noun
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.
2.
a specific fundamental set of beliefs and practices generally agreed upon by a number of persons or sects: the Christian religion; the Buddhist religion.
3.
the body of persons adhering to a particular set of beliefs and practices: a world council of religions.
4.
the life or state of a monk, nun, etc.: to enter religion.
5.
the practice of religious beliefs; ritual observance of faith.
6.
something one believes in and follows devotedly; a point or matter of ethics or conscience: to make a religion of fighting prejudice.
7.
religions, Archaic . religious rites.
8.
Archaic . strict faithfulness; devotion: a religion to one's vow.
Those are the dictionary definitions for religions. Let us see how they apply to definition of Atheism which is..
–noun
1.
the doctrine or belief that there is no god.
2.
disbelief in the existence of a supreme being or beings.
1) Neither the disbelief in a supreme being or the belief that there is no supreme being is a set of belief concerning the cause, nature, and purpose of the universe. Nor does it pertain to anything else as just as not believing in santa claus, the tooth fairy, elves, or the boogeyman or believing those don't exist either mean this as well.
2) There is no "set" of beliefs for any atheist. There are a lot of things I believe in that I know other atheist friends don't. For example, I believe that one day I'll finally be rich, they may or may not believe that. I also have different ethical beliefs than other atheists. For example I don't believe it is right for a company to charge restocking fee's to process returns. Other atheists may disagree on that ethical point.
3) This ties in with 2. Why they are listed separately I don't know but a bigger subset doesn't justify a new definition.
4) Last I checked, I never heard of a nun of atheism, or a monk, or warlock, or whatever.
I would explain the rest, but it is too stupid to do so. There is no set of ethics, practices, or observances that encompasses all atheists. There is no preachers, monks, nuns, warlocks, or the equivalent for atheism. There is no governing body, no established organization, and no need for devotion.
Again, people can be devoted to something without it being a religion. Devotion is just one PART of what entails a religion. You need the rest of the ingredients to make that pie.