The author examines the idea of "sanctity" as it emerges from the texts and the terminology of seventeenth century English Puritans. The process through which sanctity is constructed is observed within the context of the definitions given by the old and autonomous Anglican Church - according to the Sovereigns' will - with the contribution of scholars such as John Bale, who defines an authentically protestant canon of British sanctity in midsixteenth century, and John Foxe, who writes his celebrated "Book of Martyrs" in the same period. Thanks to these authors, the emphasis on "sanctity" becomes a distinctive feature of the Puritan faction by the end of sixteenth century. Through the definition of a sanctity characterized by a sudden and radical conversion and a life spent in the keeping of pure Faith, the word "saint" - with a reciprocal self-legitimation and self-validation - comes to designate the members of the "pact of the righteous", i.e. the political area which approves of regicide, prosecution of the war against the heir to the throne and acceptance of a republican government. In the evolution of its meaning, the word "saint" shares the declining fate of the faction with the end of Cromwell's Commonwealth.