It depends on how do you define atheism.
Atheism could be defined as strict denial of existence of any deity. Then it is just irrational as any religion.

Dawkins definition of Atheism is "Atheist is a person who thinks there is no compelling evidence for any existing narrative for any deity." In Dawkins definitions atheism = agnosticism.

For me I am a rationalist. I don't have a goal to believe in god. I don't have a goal to disbelieve in god. My goal is to believe in god in the universe where god exists and not to believe in god in the universe where he doesn't exist.