Both the Calvinists and Arminians hold to man being born with a sinful nature. I think the following questions are pertinent:
Is it possible for a child to be born and live his life without sin?
Are we born spiritually alive and then subsequently die spiritually only after we first sin?
Are we born spiritually dead? If so, what sin is imputed to us which causes the separation from God?
IMO, it is undeniable that the consequences of Adam's sin are on our shoulders. We bear the consequent results of what Adam did. We were not in the garden, yet we live under the curse of death brought about by Adam's transgression.
If a child is born and never sins.... he will still die. A newborn abandoned in the middle of the woods will die. He has not personally committed any sin. Why does he die?
If it is blatantly apparent that the 'sinless' newborn will physically die, then it is logical to recognize he is also born into spiritual death. What sin has the child committed to merit such a condition? None.
There, therefore, must be an imputation of sin foreign to him. God must somehow reckon something to him he has not done. He is innocent of personal sin, but he is still condemned and needs justification. But, justification from what?
This 'original sin' somehow imputed to mankind needs to be eradicated from our lives in the eyes of God. The 'sinful nature' of man needs to be somehow overlooked by God. It needs to be taken out of the equation in order for right relationship with God to be reestablished. Our justification requires the issue of 'Adam's sin' to be dealt with by God.
I've made the following statement in another thread:
It is not the mere justification of our sinful deeds which gives us right fellowship with God. It is the justification of our sinful nature. We are justified, not merely of our the sinful deeds, but of our sinful nature. Even if a person could achieve and maintain a lifestyle without sinful deeds to confess, he is still a sinner before God BY NATURE. Since the sinful nature is never eradicated during our Christian journey, we are perpetually in need of God to reckon to us a righteousness up and above any righteous behavior we can perform.
The believer who is perpetually reckoned righteous by God is at the same time a sinner by nature.
"Simul Justus Et Peccator" - At the same time righteous and a sinner.
Salvation deals with far more than the remission of our individual transgressions before God. It deals with the remission of all sin committed by us and all sin imputed to us. We are justified of all this sin because it was all imputed to Christ. Christ bore our transgressions. He took away the sins of the world. Though, we live in an actual condition of sinfulness before God, the righteousness of Christ is reckoned to us, our sin
(both personal and original) having been reckoned to him. We who are sinners by act and by nature are justified by faith in Christ.
Just as God reckons to man the foreign sin of Adam, God now reckons to man the foreign righteousness of Christ through faith.
God willing, this may greatly help some to better understand the doctrine of justification.