Article VI, paragraph 3 of the Constitution contains the "No Religious Test" Clause:
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.
At Commentary, Peter Wehner writes:
During the ratification period, the No Religious Test clause was used as ammunition by the anti-Constitutionalists. But the framers would not budge; for them, the issue was paramount. And the great 19th century legal scholar Joseph Story, in his magisterial Commentaries on the Constitution, explained why.
“This clause is not introduced merely for the purpose of satisfying the scruples of many respectable persons, who feel an invincible repugnance to any religious test, or affirmation,” according to Story.
It had a higher object; to cut off forever every pretense of any alliance between church and state in the national government. The framers of the Constitution were fully sensible of the dangers from this source, marked out in the history of other ages and countries; and not wholly unknown to our own. They knew that bigotry was unceasingly vigilant in its stratagems, to secure to itself an exclusive ascendancy over the human mind; and that intolerance was ever ready to arm itself with all the terrors of the civil power to exterminate those who doubted its dogmas or resisted its infallibility.
Story went on to remind his readers of the history of other countries, where they “found the pains and penalties of non-conformity written in no equivocal language, and enforced with stern and vindictive jealousy.”
I recount this simply to remind us that religious liberty depends on religious tolerance, and injecting sectarianism into politics has an ugly history. There are certain civic wounds that one doesn’t want to reopen.
America has achieved something remarkable in the history of nations: allowing religion to play a constructive role in the public square in a way that honors both faith and politics. It isn’t an easy balance to achieve, to say the least; and we have achieved it better than anyone. And so we don’t need ministers of any faith, including Christianity, attempting to undo what the framers created, with such great care and wisdom.