French revolution much? How about have you ever heard of Stalin or Mao? I'm not sure who tops those for inhuman atrocity. That is the world created by the worship of "reason", "intellect", and "enlightenment".
France and Europe in general was very religious during the time of the revolution. Stalin was raised by a brutal Gorgean orthodox father in A Russia that was highly religious at the time he was growing up. That he converted to atheism is irrelevant, as the hate he had for others was instilled in him by his devoutly religious and brutal raising.... much the same that Hitler's hate for humanity was instilled in him. Did you know that Hitler's father quite often beat his son to the point of unconsciousness? The elder Hitler was a devoutly religious man who beat his son daily in an effort to rid him of the Jewish blood he inherited... from his father, who was the bastard child of a Jew and whom couldn't bear the thought of being so.
In short, Stalin, Hitler, Mao and every other despotic dictator in history, whether theist or atheist, were not rational thinkers. Nor did they use reason and evidence to form the foundations of their beliefs. They were, one and all, the products of brutal religious childhoods... as almost all murderers are.
And let me step back to the subject of Hitler. He was not and never was an atheist. He was a devout Catholic. And Germany, at the time of Hitler's reign, was the most religious country in Europe. Second only to Austria, where Hitler was born and raised. Those were also the countries of origin of the most horrific and brutal series' of child rearing manuals that have ever been published. These books were written not by atheist but by Christian "doctors" and there isn't one advised disciplinary action in any of them that would land the offending parent anywhere but in prison today.
And now lets step back a few centuries to the time before the Enlightenment. Back to the middle ages when religion and the state were indeed, one in the same. Have you ever heard of an Iron Maiden? How about the Choke Pear? The Scavenger's Daughter? The Judas Chair? How about the Breast Ripper? In case you haven't, these are all torture devices that were invented by those who followed the exact tenets of the Christian Bible and they were used to punish people who were found guilty of crimes such as, say, blasphemy. That might get you a day in the shackles but if you were unpopular, it might well get you the choke pear shoved in your throat and spread to the point that your jaws and throat were ripped until they bled uncontrollably. Or if you were a woman and were found guilty of ************ or, even, flirting, you could have the choke pear shoved into your ****** and spread to the point that your innards were torn... more often than not to the point that you were left with fatal wounds. Again... for talking to the wrong person or, dare I say, having coitus with someone who paid you voluntarily and willingly.
So yeah, there are a couple of atheist dictators who have the blood of 70 or 80 million people on their hands during the 20th century and frankly, those men were monsters and not at all rational. And then you have a few dozen of centuries of murder, torture, infanticide, **** and theft of billions of individuals all in the name of basically the same invisible Sky Ghost. Some of you call him God, some Allah and still others, Yahweh. But none the less, he's the same fiction and he's still the excuse for more murders than any other excuse in human history. And, he's still being used as that excuse to this day.
As for how freedom plays out in my atheist utopia... there is no yelling in my home or in my business. There is no punishment and no violence. Our furniture doesn't get broken, nor do our walls have holes in them. We do not force our will on others and we do not support those who do. And we defend our home with guns only if that is the absolute last resort, because we value the lives of other humans, even those who would do us harm. And... we manage to live this peaceful life in the midst of the bigotry and superstition that guides our contemporaries. How is this possible? We have no enemies, because we make none.
And lastly....
"Also, without the existence of a divine law where do we even define morals? How does society decide right from wrong?"
You'll first have to prove that society and divine law have come anywhere close to defining morality or what is right. I'll give you a few easy examples....
For divine law, you'll have to explain how it is moral to murder every man and non virgin woman of a town you invade, while saving the virgin girls as *** slaves, is justified on any planet, for any reason, at any time... ever.
For societal law, you'll have to explain how it is that kidnapping and caging peaceful people who choose to imbibe a naturally occuring plant that someone else doesn't like is somehow "right".
When you've reasoned those out and when you have empirical evidence to back up your reasoning, I will listen.