I hereby declare, on oath, that I absolutely and entirely renounce and abjure all allegiance and fidelity to any foreign prince, potentate, state, or sovereignty of whom or which I have heretofore been a subject or citizen; that I will support and defend the Constitution and laws of the United States of America against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I will bear arms on behalf of the United States when required by the law; that I will perform noncombatant service in the Armed Forces of the United States when required by the law; that I will perform work of national importance under civilian direction when required by the law; and that I take this obligation freely without any mental reservation or purpose of evasion; so help me God.
The line "so help me God" is optional, and sometimes the lines "that I will bear arms on behalf of the United States when required by law; that I will perform non-combatant service in the Armed Forces of the United States when required by law" are omitted as well, if the prospective citizen can prove such commitments are in violation with his or her religion.
The Oath of Citizenship is not a federal law. Technically, any oath is legal, as long as it meets the "five principles" mandated by the Immigration and Nationality Act of 1953. These principles are:
* allegiance to the United States Constitution,
* renunciation of allegiance to any foreign country to which the immigrant has had previous allegiances to
* defense of the Constitution against enemies "foreign and domestic"
* promise to serve in the United States Armed Forces when required by law (either combat or non-combat)
* promise to perform civilian duties of "national importance" when required by law