Jewish self-definition against christianisation

Opinions regarding the movement of individuals into Judaism from Christianity and vice versa, whether as a result of coercion or free will, are a central issue and serve well as a test case for examining the attitude and behaviour of a society under duress.3 e Christian religion perceived itself from the earliest times1 is article is based on a broad on-going research project which examines attitudes of Jews towards other Jews who had converted to Christianity. Its results will be published in Apostasy and Jewish Identity in High Middle Ages Northern Europe: Are you still my brother? (Forthcoming 2015, Manchester University Press)2 Both phenomena that of departure from Jewish society and religion in favour of Christian society and religion, and its opposite continued throughout the entire period; however, they are reected very dierently in the written sources. As conversion to Christianity was a central problem with which Jewish society dealt, there are numerous and varied sources on this issue. e subject is discussed in chronicle literature, in halakhic literature, in the responsa literature in light of the numerous questions and problems which were elicited by this new situation, in liturgical poetry (piyyutim), in inter-religious polemics, and elsewhere. ose who joined Judaism were aminority who endangered both themselves and the community; hence references to them are extremely sparse and concealed in various guises.