The Reformation was an important part of England's national identity in the seventeenth century and an important part of Milton's identity. While England defined itself as a Protestant nation over against the largely Roman Catholic Continent, Milton defined himself over against Protestant opponents at home, turning his antipapal rhetoric first against prelates in the Church of England, whom he called 'more Antichristian than Antichrist himselfe' (YP i: 850), and later against the Scots Presbyters.

Milton did not consider Luther's break with Rome to be the important watershed in western history it is now regarded, and usually he did not speak of the Reformation. In his prose tracts, however, he repeatedly writes of 'reformation', by which he means the work of returning the English Church - and the English nation - to the purity and simplicity of the Gospel. Milton views the work of reformation as a recurring task. In The Reason of Church-Government, for example, he refers to the plight of Old Testament prophets 'that liv'd in the times of reformation', to a 'more perfect reformation under Christ', and to the reforming message of the Lollards and Hussites who had anticipated Luther (YP 1: 799, 757). England's role in the modern reformation is for Milton a point of particular pride, and he firmly believes that England has been chosen to complete the Reformation, in which he feels called to participate.