Even the concept of atheism is irrational. It implies the knowledge of everything in the universe.
Wow! Is there
anything that you are not completely wrong about? Or are you just projecting your own deficiencies onto others?
Instead, it is
theism that claims to have complete and perfect knowledge, whereas atheism is just saying "No, you don't have complete and perfect knowledge,
especially about the supernatural." You also believe (and depend on entirely) in
human infallibility, while we reject such a ridiculous belief.
Rather and clearly, it is the concept of
theism that is irrational, because it implies complete and perfect knowledge of the supernatural which has been passed down perfectly and without error for many generations over millennia (ie, human infallibility), all of which is completely beyond human capability.
Theists claim to have complete and perfect knowledge about the supernatural and want to sell us their bill of goods. Atheists just refuse to buy that pig in a poke.
Seeing through a swindle and not falling for it is quite rational.