Champion of El; man of God, a descendant of Cain (Gen. 4:18), so called, perhaps, to denote that even among the descendants of Cain God had not left himself without a witness.
who demands his death ...
Hitchcock's Bible Names Dictionary
(man of God), the son of Mehujael, fourth in descent from Cain, and father of Lamech. (Genesis 4:18)...
William Smith's Bible Dictionary