This article builds on contemporary debates about the doctrine of justification by faith alone to revisit the old question of the “nature of Protestantism”. Traditionally a core feature of Protestant theology, the doctrine of sola fide has been under assault for the past forty years, including within Protestant theology. This essay begins by showing that the major contemporary critique that sola fide bases salvation on a “legal fiction” misses the way that early Reformers like Luther and Melanchthon understood the doctrine very substantially in terms of its pastoral power to “console” consciences. Attending to the theme of “consolation” reveals a psychological and affective realism close to the heart of the doctrine of justification by faith alone as it was originally understood. This article then shows that traditional Protestant critiques of the reliability of external mechanisms and instruments in the mediation of grace were shaped by the same orientation to psychological and affective factors that are evident in the doctrine of justification. Together, these observations suggest that “the nature of Protestantism” may be usefully understood in terms of a foundational prioritization of psychological and affective considerations over metaphysical considerations in theology.