President Didn’t Use Bible When Taking Take Oath of Office
President Obama, like some other Presidents, was sworn in with two Bibles; one once owned by Abraham Lincoln, the other belonged to Martin Luther King Jr.
The Constitution does not require that the President swear an oath on the Bible. Article II requires that he take the following oath or affirmation: "I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."
The word “God” nowhere appears in the Constitution, and the only reference to religion is in Article VI: “no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.”