Secondly, man is sinful because Adam and Eve sinned. This unique position as federal head brought offspring where that sin was imputed. And, thirdly, no sinful person can atone for another person's sins; but only a sinless person can do it.
The subjective assumption of the punishment of God in the New Testament seemingly under stresses the fact that there is room for clemency or forgiveness. However, if we look at both the Old and the New Testaments, God's justice and His forgiveness would seem two contradicting aspects of His person. In other words, it is quite inconceivable that God's justice and forgiveness can be reconciled or can exist hand in hand. This was depicted in the Old Testament where people saw the justice of God every time they fell into sin and were punished severely for it even at the very act of performing the blood sacrifice to appease God's anger.
Part of God's creation, which, although perfect at one time, was yet disposed to be developed by man, for Adam was to care and till the garden. Here, too, the man Adam was to commence his own spiritual development which is why God endowed him with a free will. This unique position as the federal head, however, made it possible for Adam to make his preference. One choice to reach spiritual maturity was to train or develop his spirit through the exercise of obedience to the word of God, while his other choice was to lead man to reach spiritual maturity through the knowledge of good and evil. Adam would have still developed his spirit by recognizing the fact that all that is opposed to the will of God is an evil to be avoided and through voluntary resistance to such evil, to the full spiritual development or a godlike knowledge of good and evil. But by his eating of the forbidden fruit, Adam had to learn the difference between good and evil from his own guilty experience.