God: "I looked for someone to take a stand for me, and stand in the gap" (Ezekiel 22:30)
A person's life is his most precious possession. Consequently, to rob him of it is the greatest sin we can commit against him, while to give one's own life on his behalf is the greatest possible expression of love for him (1 Jn. 3:16). This, then, is the ultimate contrast: Cain's hatred issued in murder, Christ's love (issued) in self-sacrifice.
Advance in the Christian life comes not by the work of the Holy Spirit alone, nor by our work alone, but by our responding to and cooperating with the grace the Holy Spirit initiates and sustains.