How many times per day do atheists, worldwide, deny that atheism is a religion? My guess is millions. Why? Because wherever there is debate on the existence of God vs atheism, you are absolutely guaranteed that sooner or later in the discussion, the word religion will be brought in and the atheists present will be eschewing all religion.
But then some deist or theist will tell them that atheism itself is a religion, having all the telltale signs. At that point the atheists will get angry, act insulted, and arrogantly state that atheism isn’t a religion and that if atheism is a religion, then not playing tennis is a sport – or some such similar analogy (which they parrot from the priests of atheism). They radically deny that atheism is a religion because they despise religion per se and cannot endure to have their own beliefs called religion. It’s psychotic for some of them.