Orthodoxy is the defining feature of the Romanian identity, as their ethnogenesis and Christianisation were concurrent processes, and the synthesis of Latin culture and Orthodoxy protected them from Slavic assimilation, heresies and denationalisation. This study analyses the role of the Church, the printing press, Christian Humanism and the theocratic conception in maintaining unity of faith, language and nation in Wallachia, Moldavia and Transylvania.