God created the earth perfect. In this perfect earth, everything was perfect until Adam and Eve broke the one rule God gave them (Genesis 3). Today all people inherited sin from Adam and Eve. Sin is described in the Bible as a violation of the law of God (1 John 3:4) and rebellion against God (Deuteronomy 9:7;Joshua 1:18). Because of Adam and Eve’s disobedience, sin has been an “inheritance” for all of their descendants. Romans 5:12 tells us that, through Adam, sin entered the world and so death was passed on to all men because all have sinned. This passed-on sin is known as inherited sin. Just as we inherit physical characteristics from our parents, we inherit our sinful nature from Adam.
When Adam fell into sin, the result was every one of his descendants also being “infected” with sin. David lamented this fact in one of his Psalms: “Surely I was sinful at birth, sinful from the time my mother conceived me” (Psalm 51:5). This does not mean that his mother bore him illegitimately; rather, his mother had inherited a sin nature from her parents, and they from their parents, and so on. David inherited sin from his parents, just as we all do. Even if we live the best life possible, we are still sinners as a result of inherited sin.
It is illogical to think that two imperfect people could produce perfect offspring. Since Adam and Eve had both sinned and been cursed then it would be impossible for their children to be perfectly free from sin.
Being born sinners results in the fact that we all sin. Notice the progression “all have sinned and fall short of the glory of God” (Romans 3:23), we need a perfect, sinless sacrifice to wash away our sin, something we are powerless to do on our own.