“Superstitions are just coincidence or ignorance.”

Sleeping Murder (1976)

Context: I make this chief distinction between religion and superstition, that the latter is founded on ignorance, the former on knowledge; this, I take it, is the reason why Christians are distinguished from the rest of the world, not by faith, nor by charity, nor by the other fruits of the Holy Spirit, but solely by their opinions, inasmuch as they defend their cause, like everyone else, by miracles, that is by ignorance, which is the source of all malice; thus they turn a faith, which may be true, into superstition.

Letter 21 (73) to Henry Oldenburg , November (1675)

Source: Barsk: The Elephants' Graveyard (2015), Chapter 17, “Dead Voices” (p. 170)

Introduction
New Era Community (1926)
Context: We are dissipating superstition, ignorance and fear. We are forging courage, will and knowledge.
Every striving toward enlightenment is welcome. Every prejudice, caused by ignorance, is exposed.
Thou who dost toil, are not alive in thy consciousness the roots of cooperation and community?
If this flame has already illumined thy brain, adopt the signs of the Teaching of Our mountains.
Thou who dost labor, do not become wearied puzzling over certain expressions. Every line is the highest measure of simplicity.
Greeting to workers and seekers!

Preface.
A History of Science Vol.2 Hellenistic Science and Culture in the Last Three Centuries B.C. (1959)
Context: Superstitions... are nothing but persistent errors, foolish beliefs, and irrational fears. Superstitions are infinite in number and scope... It would not do to ignore them altogether, only if we should never forget the weakness and fragility of our minds. The consciousness that superstitions are rife in our own society is a healthy shock to our self-conceit and a warning.... it lets us judge ancient superstitions with more indulgence and with a sense of humor. We could not overlook them without falsifying the general picture nor judge them too severely without hypocrisy.

Source: The Goldfinch

Be it so. It proves that these donations were made long ago; and this is prescription; and this gives right and title.
Letter to Captain Thomas Mercer (26 February 1790), quoted in Alfred Cobban and Robert A. Smith (eds.), The Correspondence of Edmund Burke, Volume VI: July 1789–December 1791 (1967), p. 95
1790s

John Calvin, https://books.google.com/books?isbn=1556352468 Epistle CCC to the French church in London, 27th September 1552; translated by Jules Bonnet, p.362

Responding to audience questions during a speech in Detroit (1898); as recounted in Living My Life (1931), p. 207; quoted by Annie Laurie Gaylor in Women Without Superstition, p. 382
Context: Ladies and gentlemen, I came here to avoid as much as possible treading on your corns. I had intended to deal only with the basic issue of economics that dictates our lives from the cradle to the grave, regardless of our religion or moral beliefs. I see now that it was a mistake. If one enters a battle, he cannot be squeamish about a few corns. Here, then, are my answers: I do not believe in God, because I believe in man. Whatever his mistakes, man has for thousands of years past been working to undo the botched job your God has made.
As to killing rulers, it depends entirely on the position of the ruler. If it is the Russian Czar, I most certainly believe in dispatching him to where he belongs. If the ruler is as ineffectual as an American President, it is hardly worth the effort. There are, however, some potentates I would kill by any and all means at my disposal. They are Ignorance, Superstition, and Bigotry — the most sinister and tyrannical rulers on earth. As for the gentleman who asked if free love would not build more houses of prostitution, my answer is: They will all be empty if the men of the future look like him.