Most sources I’ve read or heard say that Pelagius argued that man is morally unaffected by the fall of Adam. Adam’s sin and fall is the example of what happens to every other soul. But those who have been influenced by Augustinian philosophy say that Adam’s sin stained everyone thereafter. One sinned and all fell, that’s the Augustinian view. But because Pelagius rejected that salvation is only offered to a specific few by a special dispensation of grace, the Pelagian opponents cast this as being anti-grace. This simply is not the case as Pelagius very much believed that salvation was a gift of grace.
Pelagius is cast as a heretic because he taught that man can take the initial steps to being saved by God. Calvinists teach that man is totally depraved so that man can do nothing towards his salvation. Calvin learned this from Augustine. Augustinian thought says that man is utterly lost and will stay that way unless God specially intervenes and restores some. Calvinists understand that salvation will not be universal, therefore they conclude that God specially intervenes for some so that they received the gift of faith to believe and do God’s will. But all of the rest not selected by God are doomed due to the original condition they supposedly inherited. This gross error is what Pelagius rejected.
Pelagius did not deny that men are sinful and in need of saving grace. But he did believe that all men, as much as Adam, choose their path to follow and obey God. And doing so by faith, they are saved by God’s grace that has been calling all men.
In defense of Pelagius, Adam sinned without any fallen nature. Why is it difficult to understand that given the same temptation, at a similar age of knowing, that all of Adam’s children follow the sin path? In other words, man doesn’t need to inherit a fallen nature to sin.
Also in defense of Pelagius, God is just and does not send people to hell who haven’t earned it as the wages of sin, Rom 6:23.
It is our just God who teaches us that justice means personal responsibility. On judgment day, each and every soul will only be judged guilty on the basis of his own sins. Deuteronomy 24:16 and Ezekiel 18:20 says that God does not punish one man for another man’s trespasses. So the very idea that Adam’s sin is passed to every soul afterward is contrary to God’s justice and can’t be true.
An Augustinian will try to smooth over the obvious injustice by arguing that the reprobate souls will be judged for their own sins and this makes the judgment just. The reality is that the reprobate souls, according to Augustine, are born already in a sinful state so as to be utterly incapable of doing anything but sin. That makes the judgment unjust.
Don’t get me wrong. I’m not saying I know everything about Pelagius or that I’m a Pelagian. But what he taught against Augustine on original sin and free will was right on.