For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
What mankind inherited was not sin of itself. If it was, there would be no babies, autistic, or young children in Heaven.
What we inherited was the "knowledge of good and evil", and thus, as soon as someone develops to the age or mental capacity to know what sin is, that person needs Christ as Saviour in their personal life.
So until and unless a person "develops to the age or mental capacity to know what sin is," that person doesn't need Christ as Savior? If a person's mentality doesn't develop to where he/she knows what sin is, are they exempt from the need for a Savior? If so, what course do they take?
There are many people who think the scriptures teach that you're exempt from 'doing your part' in the salvation of your soul for various reasons.
'Not old enough to understand what sin and death is; mentally incapable of understanding sin and its authority over us.' These are the main two. These two are thought up out of thin air to account for what some believe WE MUST DO to be redeemed (saved).
Nowhere in scripture is it said that mental illness and dying before understanding sin exempts anyone from the penalty of an unrepentant soul.
There is only on requirement for salvation; it's quoted directly by God himself. He doesn't say, 'You must understand sin;' he doesn't say, 'You must repent;' or 'You must be baptized,' or 'join the church,' or 'worship me' if you want to see the kingdom of God.'
For a surety, he doesn't say that sinners must do anything, and in fact there's nothing we can do to be redeemed. We can't do anything, something has to HAPPEN to us.
He said 'You must be born again of the Spirit of God' (John 3). He said nothing about understanding anything before this rebirth could happen.
If anyone thinks he/she played ANY PART in being born again that person is mistaken.
Jesus said nothing about understanding anything before this rebirth could happen. Please notice that when he told Nicodemus that he needed to be born again to see the kingdom of God, he made it really plain and simple that this "teacher of Israel" (bible scholar, if you will) didn't have the slightest clue of what he was trying to explain to him. It's what the writer, John wanted us to pay close attention to.
It isn't said anywhere in the narrative that Nicodemus left the meeting with a better understanding of Jesus' ministry. (He had graduated from 'Dallas Seminary' at the top of the class and was ill-equipped to teach on salvation. He could only teach the Law).
A knowledge of the Law is really important, but knowing the Law won't get anyone "born again."
The law of Moses was unable to save us because of the weakness of our sinful nature. So God DID WHAT THE LAW COULD NOT DO. He sent his own Son in a body like the bodies we sinners have. And in that body God declared an end to sin's control over us by giving his Son as a sacrifice for our sin (Rom 8:3).
No action by us can add to what God (Jesus) did. It isn't said 'Jesus' sacrifice doesn't apply unless WE APPLY for it.'
(here it is) Jesus' death on the cross doesn't redeem everybody from sin and death. You must be born again of the Spirit of God. (John 3:3,5,7)
The last thing Nicodemus said during the conversation was, "How can these things be?" In other words, 'Say what, Jesus?' He was clueless!! A scholar...!