Matthew Myer Boulton is president of Christian Theological Seminary in Indianapolis, Indiana and is a pastor in the Christian Church (Disciples of Christ). He comes from a very different theological perspective than I do, but in seeking to get to know my neighbor better, I have enjoyed his work Life in God: John Calvin, Practical Formation, and the Future of Protestant Theology. There, his educated speculation on the title of John Calvin’s Institutes of the Christian Religion is fascinating as he seeks to show how practical Calvin intended his magnum opus to be. Boulton writes:
What should we make of the Institutio's title? The most familiar English translation, "Institutes of the Christian Religion," is unfortunate in several respects. First, the phrase "the Christian Religion" rings today as if Calvin is picking out Christianity from among the world's religions, but the modern notion of "religion" had not yet taken hold in sixteenth-century Europe, and so for Calvin and his early readers, religio meant something quite different. Wilfred Cantwell Smith has argued that in Calvin's work the term religio refers to a universal, innate "sense of piety at prompts a man to worship"; Brian Gerrish has suggested that "Calvin’s use of the words religio comes closer to our own present day ‘spirituality.’" Following these proposals, Calvin’s title might be rendered today as "Institutio of Christian Piety" or "Institutio of Christian Spirituality."
Indeed, as Smith points out, for no less than a millennium in Europe, from roughly the fifth century to the fifteenth, the prevailing way the word religio was used was with reference to monastic life, a sense preserved today when I monk or nun is called "religious." Calvin was likely well aware of this traditional usage and the way it set "religious" orders apart from other clergy and, most strikingly, from ordinary like Christians, and so it is at least possible that his decision to feature this term in his title involved in implicit critique. That is, bearing in mind the common medieval usage of religio in connection with monastic orders, it is possible to read Calvin’s title – Institutio Christianae Religionis – as among other things a tacit claim that the text’s subject is the bona fide, singular, simply “Christian” religio, as opposed to the monastic varieties (the Benedictine religio, the Cistercian religio, and so on). Calvin’s use of religio may have been a terminological expression of his argument that all Christians, not only monastics, are called to be "religious" – or, put another way, that all Christians belong to a single "religious" order. Of course, precisely what Calvin had in mind with the term must remain an open question, as must the matter on how the term’s connotations resonated for his early readers. In any case, any assessment of what Calvin meant to say should include the fact that in those days the word religio had a long-standing and ongoing association with monastic life, and therefore with the spiritual, practical, and liturgical devotion ideally characteristic of that life.
But what of the title’s leading term, Institutio? And obvious option is "instruction," the word Calvin uses in his own French translation; likewise, Erasmus’s Institutio principis Christiani (1516) is often rendered in English as "The Education of a Christian Prince." Thus we might translate Calvin’s title, "Instruction in Christian Piety," or "Education in Christian Spirituality." But as we have seen, the pedagogical program Calvin had in mind is more comprehensively immersive and formational then what the terms "instruction" or "education" often connote in modern English. Perhaps for this reason, Christopher Elwood has suggested what may be the best translation of all: “Formation in Christian Piety."
As it turns out, however, Calvin left behind one other hint, by itself inconclusive, but tantalizing nonetheless. Translating Second Timothy into Latin for his commentary on that text, Calvin makes use of the term institutio at a critical juncture: the author of the epistle – whom Calvin took to be Paul – is encouraging Timothy in the life of Christian discipleship, exhorting him to “continue in what you have learned," and to remember "how from childhood you have known the sacred writings that are able to instruct you for salvation in Christ Jesus. All Scripture is inspired by God and is useful for teaching, for reproof, for correction, and for training in righteousness" (2 Tim. 3:14–16). It is a passage Calvin would have found entirely congenial to his own work as a theologian and reformer, and an exhortation he himself could have delivered to the faithful in Geneva, or indeed to his persecuted comrades in France. Moreover, since both Scripture and sanctification hold such important positions in his thought, the idea that "the sacred writings" are useful for "training in righteousness" would have been for him an especially compelling claim. Indeed, as we have seen, such "training" is at the heart of Calvin’s reforming project.
And for just this word – "training" – Calvin translates the letter’s original Greek into Latin as institutionem. The original Greek term? Paideia. Thus taking a cue from Calvin himself, we may translate Institutio Christianea Religionis as "Training in Christian Piety," or indeed as "Christian Paideia" – or, bearing in mind the pedagogical, immersive, disciplinary overtones of the word "disciple," as "Christian Discipleship."