A Letter Concerning Toleration

A short letter written in Latin in 1685, while Locke was in exile in the Netherlands, and published in 1689 with an English translation by William Popple appearing the same year. Locke argues that church and state have different ends and must be kept apart. The magistrate's task is to protect civil interests, such as life, liberty, health and property, and his only instrument is outward force. But true religion lies in the inward persuasion of the mind, which force cannot produce, so persecution is both useless and wrong. A church is a free and voluntary society; it may expel members but has no civil power over them. The state may not impose forms of worship or punish beliefs, though it may forbid actions that harm others. Locke's toleration has limits that critics often point to: he would not tolerate atheists, whose oaths he thought could not be trusted, or those who owe allegiance to a foreign prince, a remark usually read as aimed at Catholics.

It is the classic argument for religious freedom and for separating church and state, short and clear enough to read in an evening, and its limits are as instructive as its case.