Theocracy - "A system of government in which priests rule in the name of God or a god." 
Revisiting past failures
Name one theocratic government which is fair and just to all people. Please don't hold your breath while doing this or you may black out from lack of oxygen. You can look back through well over 20,000 years of history and I guarantee you won't find a single one. Even amongst the pagan and tribal cultures of our past we can see that when men rule under the supposed authority of god, injustice and inequality are sure to follow.
There is a very simple reason why secular governance triumphs over theocracy every last time. That simple reason is that some people are simply born without the capacity for belief. For some of us our rational and logical minds simply won't allow us to believe. Some of us simply value equality over the idea of fealty. We simply cannot look on as others suffer so that some may flourish.
We see this every day. People are born to religious parents and yet do not follow or believe in the religion of their parents. Many forsake religion altogether. For these people a theocratic government can be a death sentence or at least a huge obstacle to overcome.
First world problems
Many people think that a first world nation only has to do with wealth. However this misses the mark to a great extent, because we also have to acknowledge how the nation acts in terms of civil and human rights, as well as many other factors. This is why there are no countries who operate under a theocracy listed as first world nations and there never will be. The simple truth is that all religious ideologies create disparity, and disparity always leads to civil unrest.
Even the most peaceful of religions such as Hinduism and Buddhism still perpetuate social injustice that is inherent in the doctrine of the religion. The caste system and disparity of wealth present in India may now be a cultural issue, but its inception came from Hinduism and has been perpetuated, even in a society heading ever more toward secularism, by those unwilling to let go of religious idealism in the name of equality and social justice.
We're all born atheists
I wasn't born able to speak or able to walk. I had to learn to do those things. In the same respect, I wasn't born with belief. My parents as Christians taught me to accept the Christian religion and to believe in god. It took me many years to come to an acceptance that I simply don't believe that a god exists. But I didn't convert to atheism from Christianity. Instead I simply reverted back to the same state I was in before being taught to believe.
All too often we seem to ignore the fact that most atheists were once raised in a religious home and were born to religious parents, yet despite this fact, we are not believers. So when people like these all too vocal, self-proclaimed patriotic Americans say things like, "If you don't like us pushing our religion on you, you can get out", I wonder how they could be so lost. I was born here. This is my home. I deserve to be treated fairly here, regardless of my belief or lack thereof. I have a right to want equality for all people here, just as I want equality for all people everywhere. Every day there are people born on this planet who will never actually believe in a god and because of this we must understand that the only system of governance that can offer true equality is a secular government that offers equality and justice for all people regardless of belief or lack thereof.
The voice of those who have been silenced will always come to be the loudest voice crying out for justice.