I have read more than once, that Atheism is a religion, but this is not what Atheists actually think. I am almost sure that atheists believe that atheism is not a religion.
I read one long explanation, using some logic, of why atheism is not a religion. But you have to remember that logic is not just "common sense", there are rules to it that must be understood or it does not work.
In this web page, some of the ideas presented as logic in the original argument are illogical. Here is one example:
"Religion is a philosophy of life. Atheism is a philosophy of life. Therefore Atheism is a religion."
The type of logic is called deductive reasoning. http://www.philosophicalsociety.com/logic.htm
From the Columbia Encyclopedia 1946
"Deductive thinking is largely reducible to a form such as: All men are mortal. Socrates is a man, therefore Socrates is mortal (all S is P, M is S, therefore M is P); or more exactly: If all men are mortal, and if Socrates is a man, Socrates must then be mortal. Such a form is known as a syllogism."
The many problems with the author's statement begin with the faulty logical construction. This is wrong: A is B, X is B, therefore A is X. If this logic were valid, you could easily prove a dog was a cat. (A Dog is a pet, a cat is a pet, therefore a dog is a cat.)
The correct form of this logic is actually "if all S is P, and M is S, therefore M is P". The argument would have to be constructed as:
"If all philosophies of life are religions, and atheism is a philosophy of life, therefore atheism is a religion."
If the first two statements (called the major premise and the minor premise) are correct, the third part (the conclusion) must be correct. However, if either of the first two premises are incorrect, then the conclusion is also incorrect. And in this particular example, both the premises happen to be incorrect.
OK Now lets have fun playing with "logic". This time I will use my own example, with a negative twist. In order to prove that M is NOT S, you have to juggle a few things around. Let's try this: If all S is P, and M is not P, therefore M is not S.
If you substitute S=religion P=tax exempt M=atheism
All religions are tax exempt. Atheism is not tax exempt. Therefore Atheism is not a religion.
So, does the logic hold up here?
I think we should go back to teaching logic in schools, unless logic contradicts religious teaching.