Cain had set out on a bold experiment—the founding andprogressive development of a humanistic civilization based on reason alone and without reference to the divine role in human history. By simply reciting the genealogy of the succeeding four generations, the biblical author implicitly suggests there was continuity among the Cainites, the patriarch of each generation faithfully assuming the responsibilities transmitted by his predecessor.
4:18. And to Enoch was born Irad; and Irad begot Mehujael; and Mehujael begot Methushael; and Methushael begot Lamech.
By the fifth generation, however, a radical change took place that brought the descendants of Cain to a new moral threshold. The biblical writer does not explain why this development occurred, leaving us to speculate whether it might be the result of man’s unfettered reason having gone astray in the absence of a constraining higher moral authority. Lamech, the patriarch of the fifth generation, rejected the basic social philosophy of his predecessors. Instead, he adopted a new approach to human relations and the organization of society that revolutionized Cainite civilization and set it on its course of moral decay and social decline. He introduced the concept of social inequality.