Blurb:

John Teehan reads the Sermon in the light of the thesis that human morality has evolved as an ingroup adaptation and that religion has evolved to foster cooperation. Moral codes enforced by punishment of transgressors allows generosity within the ingroup, since it reduces the threat of free-riders and encourages reciprocation. Costly religious rituals allow group members to signal their commitment to group norms, and the belief in a morally interested all-knowing God that punishes evil and rewards good encourages group members not to cheat even if no human will discover their transgression. Teehan uses these insights to analyse how the Sermon forms a communal identity and moral ethos for the newly formed group of Matthean followers of Jesus. The radical interpretation of the Torah in the so-called antitheses distinguishes the group from other groups and encourages intensified trust in other group members. Alms, fasts and prayers performed in secret before the all-knowing God are a signal of commitment that cannot be judged as being insincere (hypocritical), but at the same time effectively turns those signals into a signal only to oneself and God. Instead, other costly signals, such as willingness to suffer for one’s identity, fills the function of signalling group commitment.