What to focus on in an intellectual history of 'ius gentium et naturae' for a volume on the relations between international law and Christianities? For centuries, (international) law and Christian theology maintained intensive and complex relations, which it is impossible to do justice to within the scope of this chapter. With the more recent “turn to history” in international legal scholarship, discussions of the relationship between 'ius gentium et naturae' and Christianity generally center on secularization and/or empire. For obvious reasons both sets of histories deal with early modernity – the time that the so-called 'Respublica Christiana' or Holy Roman Empire was profoundly affected by Reformations, gradually fragmented, and religious and theological fights were part of the politics of the newly emerging European nation-states.