This chapter questions the categories ‘pagans’ and ‘heretics’ that were built and maintained as a given in imperial and ecclesiastical discourses. It discusses the construction of an identity as an abstract and universal process, but profoundly embedded in specific historical, cultural, social, and material environments. Groups, but also individuals, have a propensity to mould their identities. Thus, despite an individual being classified as a Christian by late antique bishops, being Christian was not the only available alternative. An individual could activate and deactivate identities in a given situation from a situational selection of identities. The category ‘pagans’ developed by Christian writers should not be taken for granted. Instead, scholars ought to analyse the processes by means of which the late antique writers used categories such as ‘pagans’ and ‘heretics’, as well as ‘Christians’, to make sense of their world. The boundaries between groups such as late antique pagans and Christians were continuously shifting, negotiated, and redefined.