In recent decades, the `new perspective' on Paul has broken in some significant ways with broad trajectories of interpretation established by the Reformers. Proper evaluation of contemporary debates in Pauline interpretation therefore demands careful attention to their exegesis. Using Galatians 2:16, the Reformers' stance is explored in relation to (i) the works of the law, (ii) justification by faith, and (iii) the disputed genitive phrase `faith in/the faithfulness of Christ'. The interpretation of Erasmus is first explored as a contrast and a means by which to set the Reformers' exegesis in the context of sixteenth-century discussions of the text. The article concludes with a historical and theological assessment of the value of their exegesis for contemporary debates in Pauline interpretation.