Atheism is classified as another religion all over the place. Google it. The reason it is not classified so universally, is that there are atheists who don't seem to know the definition of religion, who want to classify atheism differently.
You are the only one saying that, why though? Are you trying to insult atheism by calling a religion and if you are, are you not implying that a religion is a bad thing then?
You forgot the part about doing an Internet search to see that I am not the only one saying that.
You forgot the part about checking the complete definitions of the words atheism and religion, so you can see that atheism is a religion by definition.