Within the Gospels the basic tenets of Judaism are summarised by Jesus into two initial commands: love of God, and love of neighbour; to which the third: ‘love one another’ is subsequently added. However, in the parable of the Good Samaritan, the narrative context demands that love of neighbour should be understood as a form of love for those who would be deemed as enemies by the Jesus’ audience—a point strongly reinforced by the Sermon on the Mount. Taken together, these three targets of the ‘love’ commands form the basis of group interactions within the Christian social context. Socio-cognitively these three targets may be described as interactions with prototype, in-group, and out-group: the basis of a social identity approach to group interactions. Therefore, this stream will engage with the question of enmity from within, asking how Christianity engages with these aspects of in-group and out-group interaction.
Henri Tajfel’s early explorations in social identity stemmed from his introspection about why he survived the Nazi concentration camps of World War II, largely stemming from a mistaken identity as a French, rather than a Polish, prisoner of war. From this difference in apprehension Tajfel came to understand the nature of social identity as a strongly salient component of interpersonal interaction and perception of membership in groups as introducing intrinsic bias within social engagements. This research stream blossomed with the Minimal Group Experiments, which showed that mere membership in an artificial group introduced intergroup bias within participants. The intergroup bias described by Tajfel and Turner highlights the nature of groups to construe other out groups as essentially competitive entities and contributes to their framing as an ‘enemy’ with attendant associated enmity. Intergroup enmity builds a pattern of social interactions where stereotypes and prototypes are natural cognitive mechanisms for the promulgations of these perceptions of social networks. From a theological perspective, the categorisation of groups as ‘enemy’ with inherent negative social bias challenges the ‘love’-based pattern of interaction which is construed as the basis of a Jesus-following movement. Yet, as is already seen in the Johannine Epistles, the early church struggled with how to interact with other social groups as simultaneously distinct out-groups as well as via a ‘love’ relationship.
Two millennia after this initial construal have only provided further examples of this tension at work. From the socio-religious justifications of the Crusades, through to the Protestant-Catholic divide in Northern Ireland it would appear that ‘love’ and ‘enemy’ remain distinct dialectical poles in permanent tension with one another. Often these inter group conflicts—while in the name of secular nation or state—appeal to Christian theologies of ‘love’ and intergroup interaction for traction. As can be seen in the much-repeated framing of judgement by Norman Schwarzkopf: ‘Forgiveness is up to God, we just organise the meeting.’ Nevertheless, some examples of intergroup bias minimisation sparkle amongst the dross, such as the social construal of almost 50,000 Jewish people as fundamentally Bulgarian—and therefore ingroup members—during the Holocaust, entailing their survival from the Treblinka concentration camp.
It is in this dialectical tension that this stream launches from, seeking to examine the nature of social identity within inherent intergroup bias as a framework for how group self-cognition and understanding contributes to interactions which lean towards enmity rather than love in this apparently paradoxical relationship.
 Social Identity Theory was formally described in Henri Tajfel and John C. Turner, “An Integrative Theory of Intergroup Conflict,” in Psychology of Intergroup Relations, ed. William G. Austin and Stephen Worchel (Brooks/Cole, 1979), 33–47. and has extended to a broad network of integrated approaches to the psychology of group relationships.
 Henri Tajfel, “Experiments in Intergroup Discrimination,” Scientific American 223, no. 5 (1970): 96–103.
 Penelope J. Oakes, S. Alexander Haslam, and John C. Turner, Stereotyping and Social Reality (Malden: Blackwell Publishing, 1994).
 Ostensibly ‘Caedite eos. Novit enim Dominus qui sunt eius.’ of the Cathar Crusade
 As used by various military units within modern conflicts.
 Stephen Reicher et al., “Saving Bulgaria’s Jews: An Analysis of Social Identity and the Mobilisation of Social Solidarity,” Eur. J. Soc. Psychol.36, no. 1 (2006): 49–72.