http://press-pubs.uchicago.edu/founders/documents/a6_3s27.html
§ 1843. Of the English laws respecting papists, Montesquieu observes, that they are so rigorous, though not professedly of the sanguinary kind, that they do all the hurt, that can possibly be done in cold blood. To this just rebuke, (after citing it, and admitting its truth,) Mr. Justice Blackstone has no better reply to make, than that these laws are seldom exerted to their utmost rigour; and, indeed, if they were, it would be very difficult to excuse them. The meanest apologist of the worst enormities of a Roman emperor could not have shadowed out a defence more servile, or more unworthy of the dignity and spirit of a freeman. With one quotation more from the same authority, exemplifying the nature and objects of the English test laws, this subject may be dismissed. "In order the better to secure the established church against perils from nonconformists of all denominations, infidels, Turks, Jews, heretics, papists, and sectaries, there are, however, two bulwarks erected, called the corporation and test-acts. By the former of which, no person can be legally elected to any office relating to the government of any city or corporation, unless, within a twelvemonth before, he has received the sacrament of the Lord's supper according to the rights of the church of England; and he is also enjoined to take the oaths of allegiance and supremacy, at the same time, that he takes the oath of office; or, in default of either of these requisites, such election shall be void. The other, called the test-act, directs all officers, civil and military, to take the oaths, and make the declaration against transubstantiation, in any of the king's courts at Westminster, or at the quarter sessions, within six calendar months after their admission; and also within the same time to receive the sacrament of the Lord's supper, according to the usage of the church of England, in some public church immediately after divine service and sermon; and to deliver into court a certificate thereof signed by the minister and church-warden, and also to prove the same by two credible witnesses, upon forfeiture of 500l, and disability to hold the said office. And of much the same nature with these is the statute 7 Jac. I. c. 2., which permits no persons to be naturalized, or restored in blood, but such as undergo a like test; which test, having been removed in 1753, in favour of the Jews, was the next session of parliament restored again with some precipitation." It is easy to foresee, that without some prohibition of religious tests, a successful sect, in our country, might, by once possessing power, pass test-laws, which would secure to themselves a monopoly of all the offices of trust and profit, under the national government.
“No Person shall be a Representative who shall not have attained to the age of twenty five Years, and been seven Years a Citizen of the United States, and who shall not, when elected, be an Inhabitant of that State in which he shall be chosen.”
— U.S. Constitution, Article I, section 2, clause 2
https://history.house.gov/Institution/Origins-Development/Constitutional-Qualifications/
5 U.S.C.
United States Code, 2011 Edition
Title 5 - GOVERNMENT ORGANIZATION AND EMPLOYEES
PART III - EMPLOYEES
Subpart B - Employment and Retention
CHAPTER 33 - EXAMINATION, SELECTION, AND PLACEMENT
SUBCHAPTER II - OATH OF OFFICE
Sec. 3331 - Oath of office
From the U.S. Government Publishing Office, www.gpo.gov
§3331. Oath of office
An individual, except the President, elected or appointed to an office of honor or profit in the civil service or uniformed services, shall take the following oath: “I, AB, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.” This section does not affect other oaths required by law.