Some time ago, I got into a debate with a friend of mine who claimed that atheism is a religion. Naturally, I stated that this was impossible, since atheism is the lack of a religion by definition.
So, we got into a debate on definitions. I don't know which dictionary he was using, but the definition he quoted to me for "religion" was: "any strongly held system of beliefs."
My dictionary doesn't have that definition included, but I didn't let that stop me from replying. I informed him that, if one were to use such a broad definition, then many things must be considered religions that currently don't have that distinction. My friend was (and probably still is) a staunchly conservative Republican. Politics is a very important subject to him. I asserted that his conservative Republicanism would therefore be his religion, given his definition.
He denied this, of course, but the fact remains that he has a system of beliefs that he holds himself to very strongly. By his definition, his religion would be Conservative Republicanism.
As I said, his definition doesn't appear in my dictionary. Let me share with you the definitions that do appear there. These are taken from Webster's Ninth New Collegiate Dictionary.
1 a (1): the service and worship of God or the supernatural (2): commitment or devotions to religious faith or observance b: the state of a religious [a nun in her 20th year of ~] 2: a personal set or institutionalized system of religious attitudes, beliefs, and practices 3 archaic: scrupulous conformity: CONSCIENTIOUSNESS 4: a cause, principle, or system of beliefs held to with ardor and faith
Looking at each, then... Definition 1a(1) is obviously out, since atheists certainly do not worship God. Definition 1a(2), in addition to pulling a no-no by using "religious" as part of the definition of "religion," falls short by including faith, which is something atheists don't employ. Definition 1b pulls the same "religious" no-no, but the usage is obviously not applicable. Definition 2 again uses "religious" in the annotation, thereby making full understanding of the term difficult, but still obviously being off the mark. Definition 3 is, as it states, archaic, also nebulous. And definition 4 is much like my friend's definition, with the addition of the term "faith," which disqualifies it for the same reason as definition 1a(2).
So much for Webster's.
It doesn't matter how firmly held one's atheistic convictions are. It doesn't even matter if said atheist chooses to "proselytize" his beliefs. Atheism cannot in any way be deemed a religion.
Atheism is the lack of theism. How much plainer can it get?
