Locke's work appeared amidst a fear that Catholicism might be taking over England and responds to the problem of religion and government by proposing religious toleration as the answer.

[1] In the wake of the discovery of the Rye House Plot and Charles II's persecution of the Whigs, Locke fled England to Amsterdam in the Dutch Republic in September 1683.

The question was much debated in Holland during Locke's stay, and in October 1685, Louis XIV of France revoked the Edict of Nantes that had guaranteed religious toleration for French Protestants.

[5] One of the founders of Empiricism, Locke develops a philosophy that is contrary to the one expressed by Thomas Hobbes in Leviathan, in supporting toleration for various Christian denominations.

[6] "That church can have no right to be tolerated by the magistrate," Locke argued, "which is so constituted that all who enter it ipso facto pass into the allegiance and service of another prince".

As for other practical opinions, though not absolutely free from all error, if they do not tend to establish domination over others or civil impunity to the Church in which they are taught, there can be no reason why they should not be tolerated.

Proast attacked the Letter and defended the view that the government has the right to use force to cause dissenters to reflect on the merits of Anglicanism, the True Religion.