Barth understood his study of the letter to the Romans as a conversation with Paul about God. What then can be said of Barth’s understanding of the so-called Abraham chapter in Rom 4? According to Barth, Abraham-as a historical figure or not-is only interesting insofar as he points to something that ultimately remains elusive to any historical inquiry, because it concerns the human being’s position before God. Faith is certainly crucial in this respect, and should not be misunderstood as a human achievement. It can ultimately only be apprehended in a highly paradoxical way as an “empty space” (Hohlraum). Barth’s interpretation and recent exegetical studies converge surprisingly on this point: The central theme of Rom 4 is not Abraham as such, or the Pauline understanding of “salvation history,” or the conditions of possibility of the Pauline mission towards the nations, but rather the question of God. The present contribution concludes by considering the relevance of Barth’s interpretation for contemporary exegesis.