“I never will, by any word or act, bow to the shrine of intolerance, or admit a right of inquiry into the religious opinions of others.”

The American Mercury (March, 1930); first printed, in part, in the Baltimore Evening Sun (9 December 1929)
1920s
Context: The most curious social convention of the great age in which we live is the one to the effect that religious opinions should be respected. Its evil effects must be plain enough to everyone. All it accomplishes is (a) to throw a veil of sanctity about ideas that violate every intellectual decency, and (b) to make every theologian a sort of chartered libertine. No doubt it is mainly to blame for the appalling slowness with which really sound notions make their way in the world. The minute a new one is launched, in whatever field, some imbecile of a theologian is certain to fall upon it, seeking to put it down. The most effective way to defend it, of course, would be to fall upon the theologian, for the only really workable defense, in polemics as in war, is a vigorous offensive. But the convention that I have mentioned frowns upon that device as indecent, and so theologians continue their assault upon sense without much resistance, and the enlightenment is unpleasantly delayed.
There is, in fact, nothing about religious opinions that entitles them to any more respect than other opinions get. On the contrary, they tend to be noticeably silly. If you doubt it, then ask any pious fellow of your acquaintance to put what he believes into the form of an affidavit, and see how it reads…. “I, John Doe, being duly sworn, do say that I believe that, at death, I shall turn into a vertebrate without substance, having neither weight, extent nor mass, but with all the intellectual powers and bodily sensations of an ordinary mammal;... and that, for the high crime and misdemeanor of having kissed my sister-in-law behind the door, with evil intent, I shall be boiled in molten sulphur for one billion calendar years.” Or, “I, Mary Roe, having the fear of Hell before me, do solemnly affirm and declare that I believe it was right, just, lawful and decent for the Lord God Jehovah, seeing certain little children of Beth-el laugh at Elisha’s bald head, to send a she-bear from the wood, and to instruct, incite, induce and command it to tear forty-two of them to pieces.” Or, “I, the Right Rev. _____ _________, Bishop of _________, D. D., LL. D., do honestly, faithfully and on my honor as a man and a priest, declare that I believe that Jonah swallowed the whale,” or vice versa, as the case may be. No, there is nothing notably dignified about religious ideas. They run, rather, to a peculiarly puerile and tedious kind of nonsense. At their best, they are borrowed from metaphysicians, which is to say, from men who devote their lives to proving that twice two is not always or necessarily four. At their worst, they smell of spiritualism and fortune telling. Nor is there any visible virtue in the men who merchant them professionally. Few theologians know anything that is worth knowing, even about theology, and not many of them are honest. One may forgive a Communist or a Single Taxer on the ground that there is something the matter with his ductless glands, and that a Winter in the south of France would relieve him. But the average theologian is a hearty, red-faced, well-fed fellow with no discernible excuse in pathology. He disseminates his blather, not innocently, like a philosopher, but maliciously, like a politician. In a well-organized world he would be on the stone-pile. But in the world as it exists we are asked to listen to him, not only politely, but even reverently, and with our mouths open.

Memoirs (1796)

Source: Thomas Paine From 'The Gods and Other Lectures'

319 U.S. 642
Judicial opinions, West Virginia State Board of Education v. Barnette (1943)

Source: North America (1862), Ch. 14

Source: The Martyrdom of Man (1872), Chapter II, "Religion", p. 178.

A Bill for Establishing Religious Freedom, Chapter 82 (1779). Published in The Works of Thomas Jefferson in Twelve Volumes http://oll.libertyfund.org/ToC/0054.php, Federal Edition, Paul Leicester Ford, ed., New York: G. P. Putnam's Sons, 1904, Vol. 1 http://oll.libertyfund.org/Texts/Jefferson0136/Works/0054-01_Bk.pdf, pp. 438–441. Comparison of Jefferson's proposed draft and the bill enacted http://web.archive.org/web/19990128135214/http://www.geocities.com/Athens/7842/bill-act.htm
1770s
Variant: Our civil rights have no dependence on our religious opinions any more than our opinions in physics or geometry...
Source: The Statute Of Virginia For Religious Freedom
Context: Well aware that the opinions and belief of men depend not on their own will, but follow involuntarily the evidence proposed to their minds; that Almighty God hath created the mind free, and manifested his supreme will that free it shall remain by making it altogether insusceptible of restraint; that all attempts to influence it by temporal punishments, or burthens, or by civil incapacitations, tend only to beget habits of hypocrisy and meanness, and are a departure from the plan of the holy author of our religion, who being lord both of body and mind, yet choose not to propagate it by coercions on either, as was in his Almighty power to do, but to exalt it by its influence on reason alone; that the impious presumption of legislature and ruler, civil as well as ecclesiastical, who, being themselves but fallible and uninspired men, have assumed dominion over the faith of others, setting up their own opinions and modes of thinking as the only true and infallible, and as such endeavoring to impose them on others, hath established and maintained false religions over the greatest part of the world and through all time: That to compel a man to furnish contributions of money for the propagation of opinions which he disbelieves and abhors, is sinful and tyrannical; … that our civil rights have no dependence on our religious opinions, any more than our opinions in physics or geometry; and therefore the proscribing any citizen as unworthy the public confidence by laying upon him an incapacity of being called to offices of trust or emolument, unless he profess or renounce this or that religions opinion, is depriving him injudiciously of those privileges and advantages to which, in common with his fellow-citizens, he has a natural right; that it tends also to corrupt the principles of that very religion it is meant to encourage, by bribing with a monopoly of worldly honours and emolumerits, those who will externally profess and conform to it; that though indeed these are criminals who do not withstand such temptation, yet neither are those innocent who lay the bait in their way; that the opinions of men are not the object of civil government, nor under its jurisdiction; that to suffer the civil magistrate to intrude his powers into the field of opinion and to restrain the profession or propagation of principles on supposition of their ill tendency is a dangerous fallacy, which at once destroys all religious liberty, … and finally, that truth is great and will prevail if left to herself; that she is the proper and sufficient antagonist to error, and has nothing to fear from the conflict unless by human interposition disarmed of her natural weapons, free argument and debate; errors ceasing to be dangerous when it is permitted freely to contradict them.

Letter to John Randolph (1 December 1803), published in The Works of Thomas Jefferson in Twelve Volumes http://oll.libertyfund.org/ToC/0054.php, Federal Edition, Paul Leicester Ford, ed., New York: G. P. Putnam's Sons, 1904, Vol. 109 http://files.libertyfund.org/files/806/0054-10_Bk.pdf, pp. 54
1800s, First Presidential Administration (1801–1805)

Draft Constitution for Virginia (June 1776) http://avalon.law.yale.edu/18th_century/jeffcons.asp
1770s