Present day reflection upon the burning questions of evil and violence increasingly dominate the agenda of modern society. Biblical scholarship can contribute meaningfully to this discourse by analysing biblical narratives in which the themes of violence and animosity occur. In this regard it becomes necessary to unmask the mechanisms of violence, and to examine the judgement of violence from a biblical-theological perspective. Violence and animosity are displayed very soon in the Old Testament. Genesis 4 recounts the well-known story of Cain and Abel. The story of the world's first children turns out to be the story of the world's first murder. YHWH's role in this process is of particular interest: his warnings (vss 6-7), his interrogation (vss 9-10), his sentence (vss 11-12) and his promise (vs 15). This article investigates Genesis 4:1-16 and focuses especially on the remarkable promise to Cain, the nature of Cain's mark (vs 15) and the theological significance of YHWH as the keeper of Abel's brother. Genesis 4 turns out to be a chapter with paradigmatic value for today.