The Apostle Paul tells us that sin first entered into the world through Adam & Eve (Romans 5:12-21), hence we have the term original sin. As a result all humans are born into sin and we see this acted out in many ways in the world (from greed, lust, to horrendous crimes like homicide, sexual abuse etc.). King David in his writing tells us that “Surely I was sinful at birth, sinful from the time my mother conceived me” (Psalm 51:5). The Bible teaches us that human nature has been corrupted due to sin.
No-one is good according to the Bible (Romans 3:10; only God is good: Mark 10:18). We may look at someone in a worldly context and conclude that they’re “good” (they may be known for giving to the poor, helping out others in times of need etc.). But that is ultimately worldly goodness. The prophet Isaiah once said that “our righteous acts are like filthy rags” when we are in sin (Isaiah 64:6). And, no matter how hard we try to be good we all fall short of God’s standard (Romans 3:23), and as a result we are deserving of eternal separation from God (Romans 3:26). So, when we sin we transgress (1 John 3:4) & rebel (Deuteronomy 9:7) against God himself, and this necessitates eternal separation from him. In fact, some of God’s harsh judgments of sinful people & groups in the Bible shows us exactly how serious sin is; King David said that God hates sin (Psalm 97:10). I think we cannot actually comprehend the full enormity of sin for if we did we’d try much harder to avoid it. But, according to Paul, through genuine repentance “sin shall not have dominion over you: for ye are not under the law, but under grace” (Romans 6:14).
However, the climax of the story is that God loved us so much that he made a relationship with him possible once again, thus restoring it. Jesus, by the will of God, took the sins of the world upon himself, although the Bible teaches that he was not a sinner (1 John 2:2, 2 Corinthians 5:21). I feel that this is consistent with what we experience in the world. We really see things as objectively evil and we have a conscience that convicts us; this is because God has written his law on our hearts (Romans 2:15).