Children of Abraham would have been as attentive and obedient to God’s word now as Abraham was then. They would have taken the risk of faith Abraham took, and believed God—believed Jesus—though it would mean the complete upending of their lives, just as it had meant for Abraham.
What does a civilization without God look like? Activity, growth, progress, technological advancement, wealth, sophistication, an appreciation for towering intellect, and powerful art. All stem from God's grace to humankind, yet without God, civilization degenerates.
As each new generation forged ahead with brilliance, and accomplishments, all away from the “presence of God” which Cain had left far behind him, the sense of God waned until finally, a generation was born into a time where even the thought of God was gone.
The penalty for sin is far reaching. Sin can rupture every relationship, becoming the source of untold harm both to ourselves and to others, between ourselves and God, with the power to wrench every good thing within us into ruin.
Our God-given capacity to feel, emotions that enhance our knowledge and experience of Him and each other, cover the whole spectrum of life, from ecstasy to horror, from rapture to envy, from sorrow to elation, grief to bliss, serenity to rage. Cain’s smoldering resentment, anger, hurt pride, jealousy, and envy, which he brooded over and nurtured, covered a dark spectrum that drained away his joy and delight.
What was really more wrong with Cain was not what he offered, but the condition of his heart when he offered it. God was not pleased with Cain because unrepentant sin was already in his life.