For as in Adam all die, even so in Christ all shall be made alive. 1 Cor. 15:22
The consequences of Adam and Eve’s sin went far beyond their own banishment from the Garden of Eden and the presence of God. God had appointed Adam as the federal head or legal representative of the entire human race. Consequently, his fall brought guilt and depravity on all his descendants. That is, all people (except Jesus) after Adam and Eve are born with a sinful nature. David spoke of this fact when he said in Psalm 51:5, “Behold, I was brought forth in iniquity, and in sin did my mother conceive me.” David’s sinfulness while still in his mother’s womb was not in acts of sin committed. He was referring to his sinful nature acquired at conception.
The apostle Paul explained it like this: “Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned “Romans 5:12. Note that Paul’s sentence appears to be broken off before he finished his thought. What did Paul mean in saying that “all sinned”? We could easily assume that he was speaking of the individual sins of each of us, but that is not what he had in mind. Rather he was speaking of the fact that Adam was the legal representative of all his descendants. In that sense, what he did, we did. Therefore, the consequences of his sin, in terms of both guilt and original sin, fell on all of us.
In Romans 5:18-19, Paul wrote that “the result of one trespass was condemnation for all men” and that “through the disobedience of the one man the many were made sinners”. It’s clear in Paul’s theology that Adam was appointed by God to act on behalf of all his posterity. That’s why you and I, like David, were born with original sin, and why we were by nature objects of God’s wrath.