Why is mankind fallen and disobedient to God?

Les explains that Genesis chapter 3 records the account of sin and all its horrendousness making its appearance when Adam rebelled and ate. If you understand that chapter, you understand why mankind is a fallen race, totally disobedient to everything God says, and why the fall led to 6,000 years of human suffering, degradation, corruption, evil, and wickedness; it all began in the garden. Les then points to Romans chapter 3, where God concludes this is the problem, and the only remedy is the remedy God Himself provided. That remedy flies in the face of human reasoning. Les notes that ahead of verse 19 is not a pretty picture, because that is what God sees when He looks at a human being still in old Adam—where He saw the teacher and his listeners, and where He still sees every lost person. Les describes the unbelieving individual as an opulent sepulcher, with a mouth full of cursing and no fear of God. In verse 19 Paul says “we know,” indicating solid ground, not wishful thinking or something only a theologian could dream of, but basic scriptural fact.