The original Constitution of the United States that was ratified in 1789 had only one reference to religion: [Article 6] No religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.[1]
The de facto motto of the United States, adopted as part of the Great Seal of the U.S. by an Act of Congress in 1782, was E Pluribus Unum ("Out of Many, One"). Congress changed it 174 years later (1956) to "In God We Trust."
The original Pledge of Allegiance was written in 1892 by Baptist Minister Francis Bellamy who did not include the words "Under God." Those were added by Congress 62 years later (1954), in response to the fear of communism ignited by the Red Scare of the late 40s and 50s.
"In God We Trust" did not appear on U.S. coins until 1864, and did not appear on all U.S. coins uninterrupted until the early 20th century. Its inclusion was due to appeals from devout citizens during the difficulties of the American Civil War. The U.S. didn't issue paper currency until 1861, and "In God We Trust" didn't appear on it for 96 years (1957).[2]
In a time when fear is traded like a commodity, and the word "socialism" is being used to create the same fear as the old word "communism", let's remember that our country was not founded on fear. Our nation was founded out of hope for a better world where all people were equal — that we were One From Many.
1. Original text. You can search for "religion", "religious", "God", "Christian" or other religious words. Or you can actually read the Constitution. It's not that long.