You don't seem to understand how we gain 'reason'. Do you think we just stumbled across it without some trial and error along the way or have we in the democracies arrived at the zenith of mankind and we are the heighth of all man can possibly be? I doubt it. We have to be taught 'reason' and need free ideas and expression to arrive at some 'reason' as to what life and our attitudes toward our fellow man is all about. This has been debated since the aforementioned Greeks, and perhaps earlier.The biggest thing that seems to lead to the values of freedom and rights for common people is not Christianity or any other religion for that matter. It is reason, and groups of people who are being treated differently for what they believe in, or how they look, or what class they were born into, and don't like it. Once people start using reason to think through things, they come to realize that there is no reason why a single person or a small group of people should have power over other people and be treated better. Eventually, this reasoning, along with human compassion, leads to looking at the other side as well and seeing how other people should not be treated worse just due to things such as the color of their skin or their gender.
We can see students in Universities today who feel that their education thus far has convinced them that they have achieved this 'reason' and therefore others should not have the freedom to speak their ideas, or share their values. Is this reason? No, of course no t,and yet this effort to deter others from their right to free speech has been supported by those who teach them. This would lead us to wonder what other nonsense they've been taught.
We are not near as advanced as we like to think we are and philosophies, Christianity among them, will teach us that we haven't traveled all that far.