In the previous two posts I've examined the religious beliefs of the founding fathers and have shown that the bible wasn't actually as influential as many christian apologists might have you believe. In this third part, I'm going to examine the claim that the united states was founded upon "christian principles." I mentioned this subject briefly in the first part of this series, but I'm going to go into more detail this time around. I will also address a few other claims that I failed to address in the previous two parts.
Many christians argue that because the Ten Commandments and modern legal codes include the laws "Do not steal", "Do not kill," etc. that this is grounds for a christian based legal system. Now, I agree that religion contains these ideas of no killing and stealing, but evolutionary speaking, these prohibitions would have come naturally because it obviously doesn't help the species if there is a lot of strife going on because people are taking things that aren't theirs and are killing one another.
It also seems that the idea of punishment wasn't developed with religions first. I've read some research which seems to indicate that the concept of punishment was a part of humans' primitive social groups and that would have been favored by humans' social evolution,  and therefore, religion is not needed as an explanation. When religion finally came upon the scene, it simply took this already in place idea of punishment and created a supernatural element to it. It should also be mentioned that about every religious system, even those predating christianity (such as Buddhism) contain the same prohibitions, so it's not as if civilization owes some debt to the religion of christianity for these ideas. In fact, prohibitions against killing and stealing can even be found in the Code of Hammurabi, which predates the bible by hundreds of years.
However, the main principles that the united states was founded upon, namely, a government based upon the people (instead of a god) and the separation of powers were borrowed from writers during the Enlightenment in Montesquieu and Rousseau.  These ideas heavily influenced the founders, as I have shown in the first part of this series.
A very common rebuttal to the claim of a christian nation is the Treaty of Tripoli, in which article 11 states:
"As the Government of the United States of America is not, in any sense, founded on the Christian religion; as it has in itself no character of enmity against the laws, religion, or tranquillity, of Mussulmen; and, as the said States never entered into any war, or act of hostility against any Mahometan nation, it is declared by the parties, that no pretext arising from religious opinions, shall ever produce an interruption of the harmony existing between the two countries." [emphasis mine]
This would seem to be an open and shut case but as usual christian apologists have a read-made counter at the ready (there are many but here are just two examples ).
Many christian apologists argue that the English translation done by Joel Barlow was a distorted version and the original Arabic treaty did not have article 11 in it. Whether or not that's true doesn't do anything to refute the fact that the Barlow translation was the one that was read aloud, shown to all senate members, and even signed by John Adams. There was even a copy of the treaty printed in several widely circulated newspapers, along with the following:
"Now be it known, That I John Adams, President of the United States of America, having seen and considered the said Treaty do, by and with the advice consent of the Senate, accept, ratify, and confirm the same, and every clause and article thereof. And to the End that the said Treaty may be observed and performed with good Faith on the part of the United States, I have ordered the premises to be made public; And I do hereby enjoin and require all persons bearing office civil or military within the United States, and all others citizens or inhabitants thereof, faithfully to observe and fulfill the said Treaty and every clause and article thereof."
There is no record of one person objecting to the wording of the treaty. So, regardless if it was a legitimate translation or not, everyone from the president down, agreed that the Government of the United States of America is not, in any sense, founded on the Christian religion. This fact clearly illustrates the founders' intentions. 
A second argument is that after 1805 Article 11 was not included in the new treaty. Apologists make it sound as if this fact is significant - as if that wasn't the true intention of the founders to include the "not founded on the christian religion" phrase, and was purely for political reasons. The reason Article 11 was no longer included is because recent events made it necessary to rewrite the treaty. As of 1797, the united states had never "entered into any voluntary war or act of hostility against any Mohametan nation," as was stated in Article 11. As of 1805 this was no longer true, so the treaty needed to be revised. It had to be added that the only exception to this had been to defend the right to navigate the high seas. In rewriting the sentence, Tobas Lear left out the phrase "is not in any sense founded on the christian religion." A likely reason Lear left it out was because it was unnecessary, and with what was added to the revised treaty it made the Article too long. This fact doesn't do anything to prove an apologists' case because the intention of Jefferson was to rewrite the treaty with the current situation in mind, and not with trying to prove this was not a christian nation. 
It's often been said that the "Creator" mentioned in the Declaration of Independence is said to refer to the Christian god, however, this just isn't true. As I pointed out in the second post of this series in his autobiography Thomas Jefferson noted how the majority didn't want to include any references to Jesus because it would exclude anyone who did not believe in him. The same could be said for the Christian god. The term Creator is simply a common name for the Deistic god, and not any reference whatsoever to the god of Christianity, which was a compromise, I imagine, with the founders not wanting to exclude any of the various believers in the united states, but at the same time wanting to show the secular foundation of this new nation.
Other arguments that are often used to somehow prove this is a "Christian nation" is to argue that the united states' national motto is "In God We Trust" and the fact that the Pledge of Allegiance contains the phrase "under God."
As has been demonstrated, the distortions by these historical revisionists are many and there is no doubt hundreds of claims that need refuting, though I am only one person and there are people who are much more knowledgeable than I about history so I now will point you to a few good sources about the founding of the country that I've found particularly useful:
The Faiths of the Founding Fathers, by David L. Holmes
The Founding Fathers and the Place of Religion in America by Frank Lambert
Liars For Jesus: The Religious Right's Alternate Version of American History Vol. 1, by Chris Rodda
The Separation of Church and State: Writings on a Fundamental Freedom by America's Founders, by Forrest Church (Editor)
1. Did Man Create God? Is Your Spiritual Brain at Peace with Your Thinking Brain?, by David E. Comings, M.D., Hope Press, 2008; 480-481
2. The Knowledge Book, by various contributers, published by National Geographic Society, 2007; 32
3. Liars for Jesus: The Religious Right's Alterative Version of American History, Volume 1, by Chris Rodda, Self-Published, 2006; 281-317; This book and the entire seventh chapter deals with various arguments against the sentence in question in the Treaty of Tripoli, and the many arguments christian apologists have come up with to avoid it, or attempt to counter it.
4. Ibid.; 289-290
5. Ibid.; 315-316
6. http://en.wikipedia.org/wiki/E_pluribus_unum; accessed 11-17-09
7. The Pledge of Allegiance: America's Little Hypocrisy, by Steven Schafersman - April, 2003; accessed 11-7-09