It is not required to hold the bible when taking the oath of office for President of the United States. From the wiki:

Theodore Roosevelt did not use a Bible when taking the oath in 1901. Dwight Eisenhower, Harry Truman, and Richard Nixon swore the oath on two Bibles. John Quincy Adams swore on a book of law.[3] Lyndon B. Johnson was sworn in on a Roman Catholic missal on Air Force One. Washington kissed the Bible afterwards, as some later Presidents did, but modern Presidents have not—except for Harry Truman, who bent and kissed the Bible upon taking the oath for the first time, on April 12, 1945, as well as at his second inauguration

http://en.wikipedia.org/wiki/Oath_of_office_of_the_President_of_the_United_States

>>It does seem slightly add odds (contradictory with) the principle of separation of state and church, which is usually upheld in the United States.
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>IOW, it isn't necessary?
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>>It probably must be seen in a historical context - it is an old custom, unlikely to change. Note that, while Christianity is divided into hundreds or thousands of churches, no reference to a specific church is made. Pressumably, all presidents up until now have been Christian; but perhaps the oath should be dependent on the specific beliefs (or stated beliefs) of the president; e.g., if a Moslem gets elected, the oath should be sworn on the Qur'an, or, if a Bahá'í gets elected, on the Most Holy Book.
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>Christianity has many churches, but only one book and only one God (Father, Son and Holly Spirit)
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>But, Oath being sworn on its own believe... What about? Hey guys I'm not Bahá'í anymore? What may I have to do now? On my own soul I realize that the stone's god is the one now..
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>If we take the conversation to the level of what most cost to my life... A blackmail sounds the most logical answer for each new president that will come.. No??
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>>>Here is a good question for those peoples that loves relativism..
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>>>Why not Obama's Oath under Koran and/or Allan Kardec's books.. Humm, why not under books of black magic??
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>>>Why Holly Bible?
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>>>What about not a list of the most known... I mean, every president has to do several oaths with the right hand under every new book that represent a new religion.
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>>>Today we have.. at least 10 big religions and something as 10.000 sects. Maybe 6.000 on Africa, 1.200 only in USA and dozen in others countries.
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>>>What about for the atheist people... Huuuum... right hand under his own heart, it doesn't sound a little suspect?
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>>>Huummm, why not under his football flag team?
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>>>Huumm, I hope that I'm not starting the 3rd world war here <g>
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>>>If we're creating a figure of our creator only based on ours own image.. Is this a kind of hard equation??