Grace and Freedom addresses the issue of divine grace in relation to the freedom of the will in Reformed or "Calvinist" theology in the late sixteenth and early seventeenth century. It focuses on the work of the English Reformed theologian William Perkins, especially his role as an apologist of the Church of England, defending its theology against the Roman Catholic polemic, and specifically against the charge that Reformed theology denies human free choice. Perkins and his Reformed contemporaries affirm that salvation occurs by grace alone and that God is the ultimate cause of all things, but they also insist on the freedom of the human will and specifically the freedom of choice in a way that does not conform to modern notions of "libertarian freedom" or "compatibilism." In developing this position, Perkins drew on the thought of Reformers such as Peter Martyr Vermigli and Zacharias Ursinus, on the nuanced positions of medieval scholastics, and several contemporary Roman Catholic representatives of the so-called "second scholasticism." His work was a major contribution to early modern Reformed thought both in England and on the continent. His influence in England extended both to the Reformed heritage of the Church of England and to English Puritanism. On the continent, his work contributed to the main lines of Reformed orthodoxy and to the piety of the Dutch Second Reformation.

Unity in Diversity presents a fresh appraisal of the vibrant and diverse culture of Stuart Puritanism, provides a historiographical and historical survey of current issues within Puritanism, critiques notions of Puritanisms, which tend to fragment the phenomenon, and introduces unitas within diversitas within three divergent Puritans, John Downame, Francis Rous, and Tobias Crisp. This study draws on insights from these three figures to propose that seventeenth-century English Puritanism should be thought of both in terms of Familienähnlichkeit, in which there are strong theological and social semblances across Puritans of divergent persuasions, and in terms of the greater narrative of the Puritan Reformation, which united Puritans in their quest to reform their church and society.