Was the United States founded on Christianity?
The quotation often given is in fact from Article XI of the Treaty of Tripoli (8 Stat 154, Treaty Series 358):
"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 or enmity against the laws, religion or tranquility of Musselmen--and as the said States never have entered into any war or act of hostility against any Mehomitan 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."
The text may be found in the Congressional Record or in treaty collections such as Charles I. Bevans' Treaties and Other International Agreements of the United States of America 1776-1949, vol. 11 (pp. 1070-1080).
The Treaty of Tripoli was signed in Tripoli on November 4th, 1796. The English text of the treaty was approved by the U.S. Senate on June 7, 1797 and ratified by President John Adams on June 10, 1797. It was recently discovered that the US copy of the Arabic version of the treaty not only lacks the quotation, it lacks Article XI altogether. Instead it seems to contain the text of a letter to the Pasha of Tripoli from the Dey of Algiers.
The person who translated the Arabic to English was Joel Barlow, Consul General at Algiers, a close friend of Thomas Paine--and an opponent of Christianity. It is possible that Barlow made up Article XI, but since there is no Arabic version of that article to be found, it's hard to say. It seems unlikely, however.
In 1806 a new Treaty of Tripoli was ratified which no longer contained the quotation. The 1815 Treaty With Algiers contains a similar article, but does not state that the US government is not founded on religion, only that it is not incompatible with any religion.
Ignoring the question of the wording of the Arabic version of the 1796 Treaty of Tripoli, we can conclude that the wording of the English article XI fairly represents the opinion of the time, as it was passed and approved by both the US Senate and the President.
I'm curious as to your opinion on the matter. Introduce anything you'd like into the discussion. Just, don't be belligerent or try to proselytize me.