Paul in chapter 5 of Romans has stated that much has come to us through justification by faith. It is in the last half of the chapter where he told us the greatest benefits. Previous to our faith in Christ we have been totally identified with Adam, and our fate has been sealed with him. Now in Christ we have been liberated from our connection with Adam and we now belong to Christ and are fully identified with him. Before Paul talked about the benefits of being in Christ, he told us what happened to us in Adam.
12 Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned with him (Rom 5:12)
Sin and death entered the world through Adam. We must remember that humanity is a profound and deep unity. We are totally dependent upon our predecessors for what we have become. It is not only through our DNA that we are connected to our past all the way back to Adam, but it is also spiritually that we are connected to Adam. His choices in the garden have become our day by day reality. But the wonderful thing in through the second man, the last Adam, we now are totally identified with Christ. Christ is inseparable from us and we are inseparable from him.