This article integrates the concept of sovereignty with religious perceptions of misrule in the years leading up to the English Civil War. Existing revisionist narratives have emphasized the consensual nature of early Stuart political culture, especially the central role of the ‘common law mind’ in determining the proper place of potentially rival political vocabularies of natural law, civil law and absolutism. This article argues alternatively that the concept of sovereignty and in particular the contested relationship of sovereignty to ecclesiastical governance stood at the centre of the emerging conflict. The primary mode of ‘opposition’ to the policies of Charles I’s personal rule (1629–40) was erastian: it presumed that control over the doctrine and discipline of the established church was for all intents and purposes a mark or right of sovereignty in the same manner as power of war and peace, power of appointing magistrates, or coinage. Seen in this light the ecclesiastical innovations of the personal rule constituted a treasonable attempt on the part of the Laudian episcopate to erect an ecclesiastical state within a state. The English Civil War was a war of religion in the sense that a significant number of those who waged it operated under the assumption that religion was the rightful provenance of the civil magistracy of king in parliament.