This thesis offers an examination of a century-long tradition of religious sonneteering in early modern England. By accommodating a new understanding of the sonnet as genre rather than strictly as form, it proposes a way of thinking more subtly and flexibly about the ways in which we define ‘sonnethood’: that is, in terms that no longer equate ‘sonnethood’ to a mere shell or mould of a form but that also give due consideration to the cognitive and experiential dimensions that inhere in sonnet practice, sonnet thinking and sonnet expression. The case studies that comprise this thesis invite readers to reconsider the relationship between the kinds of thinking certain verse-forms make possible and certain characteristic ways of posing, thinking about, and working out problems of theological belief, particularly at a moment in history when Christian confessional identity was perhaps at its most labile, and hence its most precarious. What this ultimately amounts to here is an examination of the theological potential of the sonnet form, of some of the characteristic ways in which sonnet thinking suggests itself as a particularly congenial mode of expression for fleshing out dilemmas of faith and belief, and of the ways in which theological concerns can become constitutive of the formal properties of a poem, and vice versa. Each chapter of this study therefore takes as its point of departure a certain key element of the early modern English religious sonnet as it is instantiated in or brought into relief by the sonnet practice of a particular author over the course of a century’s span: scriptural and poetic intersections in Lok; twinning and conversational poetics in Herbert; the conversionary trajectory of sonnets in Donne; and mathematical and eschatological thinking in Milton. While each of the case studies that comprise this thesis is organised around a distinct element of sonnet practice which each of the four chapters that follows shows acutely manifest in the devotional poetic of a particular post-Reformation English author, they all bear on an underlying assumption about the theological implications of verse-form in the early modern period. This thesis proposes that sonnets enjoyed a particular status as a vehicle of devotional contemplation in early modern England. To view the religious sonnets of Lok, Herbert, Donne and Milton through the lens of this one central organising insight is to bring into new focus the profound devotional and intellectual energies of the sonnet as a mode of understanding and as a way of thinking in the greater theological economy of sixteenth-and seventeenth-century England.