Is communist Russia objectively worse than the crusades or the Catholic inquisition or ISIS? Let's just be honest here and say that human being are capable of pretty cruel things, regardless of being spurned by religion or not.

And why is atheism a religion. Isn't its definition a lack of religion?

> Is communist Russia objectively worse than the crusades or the Catholic inquisition or ISIS?

In numbers, yes.

> Isn't its definition a lack of religion?

I thought it was defined by the lack of belief in deities / supernatural powers. I might be wrong.

Even if true, you can't compare the death toll of post industrial WWII and the crusades on numbers alone.

Precisely. A lack of belief.

If you want to argue that, also take a good look at the French Revolution.

> A lack of belief.

In deities and supernatural powers.

In other aspects I find many forum atheists to believe strongly in theories that are way above their heads.

The atrocities committed during these periods were not made in the name of atheism, which is the main difference with ISIS or inquisition. Whatever they did, it was not consequence of their atheistic beliefs.

Atheism isn't a religion any more than Gentile is a religion.