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.