Reflecting on Atheism.

[Optimistic Mysanthrope]

This presupposes that they had religion and theology in the first place. Which is what the question is about. Because if pagan Greece and Rome did not have religion, then what they were discussing about teaching in schools could not have been 'theology' or 'religious information'.

And before someone tells me about the Greek 'gods' Zeus, Thor, Athena, and the stories about them, the temples, the rituals etc etc, I'm very well aware of all that, but what makes all those practices into religion.

I would say that the belief, myths, temples, rituals, worship etc are precisely what makes those practices into religion.

What is Religion anyways?

That's not an easy question to answer. Do you have a definition that would exclude pre-christian beliefs?

and minor point: they didn't see their "gods" (another Christian theological concept) as supernatural agents.

Hang on there sparky, what definition of 'supernatural agent' are you using? All the gods you've mentioned so far would easily fit into my definition.

and more importantly, we have to remember that the term 'Religion' itself was born out of Christian theology. and this brings us right back to the title of the thread. If 'Religion', 'God', 'gods', 'theism' are all Christian theological concepts, then what is Atheism?

How the terms came about is generally irrelevant when considering what those terms apply to.