“State interference is an evil, where it cannot be shown to be a good.”

Source: The Prince (1513), Ch. 12; translated by W. K. Marriot

The Mike Wallace Interview (1958)
Context: The separation of church and state is necessary partly because if religion is good then the state shouldn't interfere with the religious vision or with the religious prophet. There must be a realm of truth beyond political competence, that's why there must be a separation of churches, but if religion is bad and a bad religion is one that gives an ultimate sanctity to some particular cause. Then religion mustn't interfere with the state — so one of the basic Democratic principles as we know it in America is the separation of church and state. … A church has the right to set its own standards within its community. I don't think it has a right to prohibit birth control or to enforce upon a secular society its conception of divorce and the indissolubility of the marriage tie.

537-539
Fruits of Solitude (1682), Part I
Context: A good End cannot sanctifie evil Means; nor must we ever do Evil, that Good may come of it. Some Folks think they may Scold, Rail, Hate, Rob and Kill too; so it be but for God's sake. But nothing in us unlike him, can please him.

In 1837 http://stoprepublicans.blogspot.com/2008/06/democrats-held-these-words-to-be-self.html
1830s

Source: Heaven and Earth

Source: The Essays: A Selection

Non-Violent Resistance - Often misquoted as "You assist an evil system most effectively by obeying its orders and decrees. An evil system never deserves such allegiance."
Posthumous publications (1950s and later)
Context: You assist an unjust administration most effectively by obeying its orders and decrees. An evil administration never deserves such allegiance. Allegiance to it means partaking of the evil.
A good person will resist an evil system with his whole soul. Disobedience of the laws of an evil state is therefore a duty.

Hope and Memory: Reflections on the Twentieth Century (2003)