Affirm Rather Than Swear
There has been alot of misinformation concerning the traditions of taking oaths. The subject can be dealt with in two parts, and in fact has been dealt with as such in law. The first being the swearing in of witnesses in civil and criminal proceedings. The second, the taking of an oath of office. Alternatively, we can break it down by treating the tradition of the raised right hand separately from the left hand on the Bible. Let's have a look at the right hand first.
In his book, History of American Law, Lawrence M. Friedman writes: "Burglary was punished in all the colonies by branding with a capital B in the right hand for the first offense, in the left hand for the second, "and if either be committed on the Lord's Daye his Brand shall bee sett on his Forehead as a mark of infamy." In Maryland, every county was ordered to have branding irons, with the lettering specifically prescribed: SL stood for seditious libel and could be burned on either cheek. M stood for manslaughter, T for thief, R for rogue or vagabond, F for forgery. In Maryland and Virginia a hog stealer was pilloried and had his ears cropped. For a second offense he paid treble damages and was burned with the letter H on his forehead. Double punishment if the hog stealer was a slave. The third offense brought death."
So, upon entering a colonial courtroom, if the judge did not see a visible brand on your forehead, you were asked to raise your right hand in order to determine whether you had a criminal history. That part of the tradition has nothing to do with religion. These barbaric ways were abandoned as the nation was formed and laws codified. But for whatever reason, the tradition of raising the right hand persists. For everyone except the Quakers, the swearing of an oath to the christian god while placing a hand on the Bible also persisted.
Since 1689 the right of Quakers to give an affirmation has existed in the United Kingdom through the Tolerance Act. The text of the affirmation was the following: "I A.B. do declare in the Presence of Almighty God the Witnesse of the Truth of what I say." The right to give an affirmation is now embodied in the Oaths Act 1978, c.19, which prescribes the following form: "I, do solemnly, sincerely and truly declare and affirm," and then proceed with the words of the oath prescribed by law, omitting any words of imprecation or calling to witness. Quakers had very sensible reasons for their belief. Jehovah's Witnesses hold the same view.
Quakers did not get the same consideration in colonial South Carolina until 1715 and in North Carolina it even lead to the "Cary's Rebellion". The final draft of the 1787 Constitution of the United States makes four references to an "oath or affirmation": In Article I, Senators must take a special oath or affirmation for the purpose of sitting as the tribunal for impeachment; in Article II, the president is required to take a specified oath or affirmation before entering office; in Article VI, all state and federal officials must take an oath or affirmation to support the U.S. Constitution; and in Amendment IV, all warrants must be supported by evidence given under oath or affirmation. So, we have much to thank the Quakers for. Although their reasoning was religious, they forced a change in the law first to move away from the word "oath" and furthermore to be more accepting of conscientious objection and varying religious views.
Back in Britain, Charles Bradlaugh, who helped to establish the National Secular Society (an organisation opposed to Christian dogma), helped to pass the Evidence Further Amendment Act 1869 which gave atheists the right to affirm in court. His greatest success was the introduction and passage of the 1888 Oaths Act, allowing universal affirmation as an alternative to the oath. This covered oaths of office as well.
Concerning oaths of office in the States; Franklin Pierce was the only President known to use the word affirm rather than swear. Theodore Roosevelt did not use a Bible when taking the oath in 1901. There are no known inauguration Bibles for presidents John Adams through John Tyler; in fact, there's no concrete evidence that those early presidents used a Bible at all for the oath. Dwight Eisenhower, Harry Truman, and Richard Nixon swore the oath on two Bibles. John Quincy Adams swore on a book of law. Lyndon B. Johnson was sworn in on a Roman Catholic missal on Air Force One. Washington kissed the Bible afterwards, and subsequent presidents followed suit, up to Harry Truman, but Dwight Eisenhower broke that tradition by saying his own prayer instead of kissing the Bible.
Nothing in the Constitution requires that the oath of office be taken on the Bible. Neither do the words "so help me God" appear in the oath. While Presidents often include this phrase in their inauguration ceremonies, the words are customary; they are not required by the Constitution and have no legal significance. The Constitution requires nothing of federal officers in the way of religion. The framers saw no need to refer to God in the oath of office, and explicitly provided an alternative to the oath that guaranteed secularity. An affirmation has no religious conotation.
There are, however, still places in the United States where you may have trouble taking public office without swearing an oath to the judeo-christian god. Our own Herb Silverman of the Secular Coalition of America won a unanimous decision in the South Carolina Supreme Court, which struck down the religious test requirement for holding public office in that State. This was possible not only because of the relevant wording in the Constitution, but also because of the U.S. Supreme Court ruling in Torcaso v. Watkins in 1961.
According to The Free Dictionary.com An affirmation is "a solemn and formal declaration of the truth of a statement, such as an Affidavit or the actual or prospective testimony of a witness or a party, that takes the place of an oath. An affirmation is also used when a person cannot take an oath because of religious convictions." In the United States, generally, all witnesses who declare themselves conscientiously scrupulous against taking a corporal oath, are permitted to make a solemn affirmation, and this in all cases, criminal as well as civil. In France, the laws which allow freedom of religious opinion, have received the liberal construction that all persons are to be sworn or affirmed according to the dictates of their consciences; and a quaker's affirmation has been received and held of the same effect as an oath. For the violation of the truth in such case, the witness is subject to the punishment of perjury as if he had been sworn.
About.com reasons: "There are good political and ideological reasons for affirming an oath rather than swearing. Expecting people in court to swear an oath to God while using a Bible only helps reinforce Christian Supremacy in America. It's not just a "privilege" for Christians that courts incorporate Christian beliefs and text into legal procedures, but instead a form of supremacy because they are receiving official state approval and citizens are expected to actively participate. Even if other religious texts are permitted, it still means that the government is favoring religion in an inappropriate manner. Finally, there are good legal reasons to affirm rather than swear an oath. If you swear to God on a Bible when you don't believe in either, then you doing the opposite of what you are supposed to. You cannot reliably promise to tell the truth in a ceremony where you are lying about your beliefs and commitments."
If the question put to you is not "Do you swear or affirm..." but simply "Do you swear to..." just respond with "I prefer to affirm." You can read Dave Silverman's personal experience and how smoothly that went. Don't think that you are "outing yourself as an Atheist simply by choosing to affirm. t only means you don't "swear to God". For all anyone else knows, you could be a Quaker, Jehovah's Witness, Mennonite or any number of things.
Discuss further in the About.com Atheism forum