In this work, Jeehei Park proposes Greek and Roman cosmopolitanism as a constructive category through which to navigate a reading of human diversity and communal unity in Paul's letters. Park takes a thorough look at the cosmopolitan ideas of Diogenes of Sinope, Philo, Plutarch, Epictetus, and Marcus Aurelius to establish Paul as an interlocutor who critically participated in the discourse of cosmopolitanism. Park characterizes Paul's understanding of unity with the distinctive phrase "heterogeneous unity," in which human differences are respected and embraced rather than being universalized or homogenized. This book offers a novel analysis of Paul's rhetoric about citizenship in Philippians and its adoption of Greek and Roman cosmopolitanism as an interpretive contour.