Fact Check: Is It Illegal To Be Sworn Into Office On The Quran?
No, it is not illegal to be sworn into office on the quran. Member-elects may be sworn into office on any text they choose, or nothing at all.
The Constitution states, “No religious Test shall ever be required as a qualification to any Office or public Trust under the United States.”
The Senators and Representatives before mentioned, and the Members of the several State Legislatures, and all executive and judicial Officers, both of the United States and of the several States, shall be bound by Oath or Affirmation, to support this Constitution; but no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.
Furthermore, a report from the Congressional Research Service states:
As the Members-elect raise their right hands, they are not required to hold anything in their left hands. Many have held a family Bible or another sacred text in their left hands, but there is no requirement that anything be held when the oath is taken.