The Puritans strongly criticised the ecclesiastical authority of the Roman Church, which claimed a monopoly of Scripture interpretation. For the Puritans, every believer, literate or illiterate, could read God’s Word for himself, as he would be guided and inspired by the Holy Spirit towards clear discernment. This doctrine of illumination, to which the Puritans subscribed, contributed largely to shaping the orthodoxy of Protestant theology. Nevertheless, the Puritans fell into self-contradiction when censuring the Family of Love whose followers they regarded as non-Christians. This article examines these contradictions, which have been generally neglected by historians, studying the conflicting relationship between Puritans and Familists, and attempting to determine how the latter capitalized on these contradictions in order to counteract their Puritan detractors and to legitimise their faith.