I agree on the conclusion (atheists are religion), not so much on the why (the things they revere).
I would argue they are a faith based religion because atheism implies certainty or strong conviction towards the lack of a god. Since god is not falsifiable it requires the same amount of faith to claim he is real as it takes to claim he isnt. Therefore atheists are faith based. Only an agnostic, someone who makes no assertions about a god's existence, can truly claim a non-faith based opinion.