The Constitution, the golden standard of American law, never mentions God or even anything about religion (Butler 159). This is considered one of the most secular documents of the modern world (Butler 159). Article six must definitely contribute to this notion; it states that no religious Test shall ever be required as a Qualification to any Office of public Trust under the United States (Butler 159). Some argue that the Constitution is an explicitly Christian document. In actuality, Article Six explicitly states that the United States must never be a Christian nation, or any other religious nation for that matter. If this is not convincing, the First Amendment to the Constitution, passed by the first congress in 1791, should be Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof (Butler 148). Thomas Jefferson made clear his position that the First Amendment was in place to create a wall of separation between church and state (Butler 148).
Thomas Jefferson's Declaration of Independence was also a very secular document. Although religion did enter the Declaration of Independence its focus was clearly to address the offenses of British politicians. No religious issues were included in the history of repeated injuries and usurpations section of the Declaration (Butler 133). I do not believe this was an accident or that Jefferson somehow forgot to mention them.
The only religious phrases found in the Declaration of Independence are not specifically Christian. As an example, the phrase the laws of nature and nature's God shows that Jefferson did not think our rights are not given to us by a divine being but rather by the natural law. Divine providence is used to reference that which Americans would rely on for protection (Butler 133). A Supreme Judge of the world who would judge the rectitude of our intentions was also mentioned (Butler 133). God or Christ were never mentioned.
Young Freethought: America Is Not A Christian Nation