Purpose indicate a meaning an objective that a group of people have in regarding to something (deity, money, health, other...).
Atheists don't believe in God but they don't have a faith: so the word purpose has no meaning to them.
You know that. I know that. Try explaining that to BADecker.
Look, even if atheist all thought that the universe doesn't have a purpose - not all of them think this way -
Yes, they do. If the universe has a purpose it must have a creator. If you believe in a creator, you're not atheist.
the definition that uses the word "purpose" is only one of many definitions. Atheism is a religion, but if somehow it is not, it is so extremely close that it may as well be considered religion.
Can I summarise your statement? "Atheism is a religion. Even if it isn't a religion, it's a religion".
This is not an argument, it's just a self contradictory statement.