First I'd like to point out that the author was a kook who is still only popular because Glen Beck's favorite writer. The book's whole premise is 'The founding fathers created America because God said so. Praise Jesus'.
The United States was never a Christian nation, and this book would make Thomas Jefferson and and J.Adams roll in their graves.
http://www.salon.com/news/feature/2009/09/16/beck_skousen/print.html
Why 5000 years, why not 2000 or 8000? Why not 12000 years. The one invention that lead to everything we have today was probably the plow, but even thousands of years before humans knew how to use tools and started wearing clothes 25-30 thousand years back. As you can see it wasn't a 'leap' and it certainly didn't start 5000 years ago.
The ideas in the Declaration and Constitution certainly didn't come from God either. They came from thinkers like Plato and Cicero who were certainly no Christians.
The content of the book itself is often factually wrong and seems like a poor attempt to rewrite history by the conservative religious right. How did the author miss the part in the constitution about separation of church and state?
When has christianity been about liberty anyway? During the Inquisition? When they took over the Americas? When they tortured and enslaved the indigenous people of every continent they came across? When they accepted homosexuals to be free to marry each other... oh wait.
Now if you want to move beyond the stupidity and intelectual dishonesty of this book we can talk about what freedom is and where the ideas come from.
Freedom is not a universal value. There are 3 different concepts of freedom; national freedom (freedom from other nations), political freedom (freedom to have the right to vote, choose officials and run for office), and individual freedom (freedom to do whatever you please as long as you harm no one else). Historically, the only other nation that had all 3 types of freedom before the US, was Athenian Democracy. Aside from that, most countries willingly chose one type of the 3 over another. The Roman Empire had political and individual freedoms, but no national freedom. North Korea has national freedom, but they sacrifice individual and political freedoms.
Some civilizations(China, Egypt) didn't even have a concept of freedom and they did just fine( even if we don't necessarily agree) Freedom is not a universal value, it's mostly an idea of western philosophy, not that that's a bad thing.
