In Genesis 4:23, this signifies to extinguish faith. (Arcana Coelestia 427)

'The slain of Jehovah' signify people who turn truths into falsities, which causes them to perish.

'The slain,' in Lamentations 2:12 signify people who do not know what the truths of faith mean.

'The slain' when referring to the Lord in Revelation 5 means the separation of everything from the divine. In denial of His divinity, He is spiritually slain to people and this denial causes a state of separation from Him.

(References: Lamentations 2; The Apocalypse Explained 828)