Recent studies have discussed Paul's letters against the backdrop of ancient Greek philosophy, particularly of Stoicism, Platonism and Cynicism. This article will take up the latter suggestion, as it shows significant similarities between Paul's argument in Rom 1–2 and the Cynic tradition, which is a neglected aspect in scholarly discussion. A comparison of Rom 1.18–32; 2.14–29 and the Cynic epistle Ps.-Diogenes, Epistula 28 will outline decisive assumptions and argumentative patterns that both letters have in common.