Mont. Const. art. III, § 3

Oath of office. Members of the legislature and all executive, ministerial and judicial officers, shall take and subscribe the following oath or affirmation, before they enter upon the duties of their offices: "I do solemnly swear (or affirm) that I will support, protect and defend the constitution of the United States, and the constitution of the state of Montana, and that I will discharge the duties of my office with fidelity (so help me God)." No other oath, declaration, or test shall be required as a qualification for any office or public trust.