The Great Flood wiped out everybody except Noah, his sons and their wives. It was their righteousness that saved them, but this catastrophe was not something God wanted to repeat.
There is little doubt that moral strictures change over time. When I was young, a teenager having sex was immoral. Now, it’s deemed normal, and celebrated on television. Drug use used to be immoral, now it’s recreational. The specifics of what constitutes moral behavior differs from culture to culture and religion to religion, and in some cultures and religions the definition hasn’t been as malleable as it has in the west. Nevertheless, this confusion and variety begs the question: is there an absolute morality given by God, or are we just making it up for our own convenience?
In the Biblical story of the Great Flood (Genesis 6 – 9) God decides to destroy all of creation because of the immorality of humanity. Everybody, everywhere, is doing bad things, and God can’t stand it anymore. The question is: did humanity know they were doing bad things? After all, there were no 10 commandments, no Levitical laws. There were no contractual agreements between humanity and God. How was “good” differentiated from “bad”? But, somehow, people knew the difference anyway, since God finally decides to spare Noah and his sons and their wives because they are righteous – they have lived in accordance with God’s as yet undefined law.
The simplest answer to this conundrum is that when Adam and Eve ate from the Tree of the Knowledge of Good and Evil, they absorbed this knowledge and passed it on to their heirs. So, all of the behavior that God objected to in the time of Noah was knowingly bad – the people knew the difference and were ignoring the good in favor of the bad. In other words, humanity had an intrinsic knowledge of good and evil long before they had codified rules defining good and evil.
This makes God’s covenant after the flood all the more remarkable. God is going to recreate the world through Noah’s sons and their wives, and he is going to let things play out. Immorality clearly continues: it makes up the grist for most of the subsequent Biblical stories. But there is an unspoken yet clear component at the heart of God’s promise to Noah: God is saying, “When I say I will not abandon humanity, it means I will provide help along the way.” God promises not to be an absentee landlord; God promises to stay involved in history; God promises to provide concrete parameters, like the Law. Ultimately, God is promising humanity a savior (Christ) who will not only make clear the essence of moral behavior (Christ’s teachings), but will also provide the means for us to choose righteousness over sin (redemptive salvation) by his efforts, not ours.
We love the folksy tales of the animals going two-by-two aboard the Ark, and the beauty of God’s rainbow promise. But there is a deep seriousness embedded in this, God’s first covenant with humanity. It sets the stage for all that is to follow. It places humanity in a covenantal relationship with the Divine, where even our own infidelity can not shake God’s commitment to his creation. Our moral behavior, based on intrinsic knowledge illuminated by Christ, is the marker along the pathway that keeps us pointed towards the New Jerusalem.