Is there a "second chance" for salvation.

[CaspianSails]

<CS>No, there is no scriptural reference to a second chance. Category 5 is the trickiest if you consider Romans chapter 1 and in particular verses 19 and forward.
Category 4, oh yes. I have a child, now with her heavenly father who was born with a genetic condition which affected her central nervous system. I won't get into it but her mental development ceased when she was three years old and regressed the remainder of her life. There is no scripture that categorically states that a person in that state is given a pass, if there is I have not read it. However, there is a scripture that says God will have mercy on whom He will have mercy. Romans 9:15. I only say this because if you believe Romans 5:19 then you would believe that all people are born into sin, there is none righteous no not one. Take into account 2 Samuel 12:23 where David's son had died because of David's sin. This verse clearly teaches that David would go to his son. There is enough evidence to support the idea that God's mercy is given where it is applicable. So your category 4 is not so much a second chance, I would reject that phrasing but is God's mercy and love. I don't really think you meant 4 as a second chance anyway, just wanted to clarify my response on that.
There is a case to be made that Category 5 could be affected by Romans 9:15. I will comment though, the basis is quite thin. I think you would be hard pressed to find a civilization today where the Gospel has never been shared.
In the end we are not God. God has given a path, a gate, a door which is the only way to salvation. Enter the gate and walk the narrow path and be saved.<CS>

Romans 4:15
(15) Because the law worketh wrath: for where no law is, there is no transgression.
Romans 5:13
(13) (For until the law sin was in the world: but sin is not imputed when there is no law.​

These vss. apply to everyone who has not heard or could not understand scripture; infants, small children, mentally challenged, etc.

To your point of those who are incapable of understanding sin or right from wrong I will not argue and agree and thank you for pointing out those versus, which frankly, I would typically read over and not dwell on as they are part of a larger frame of reference in context of the over reaching point Paul was making in terms of Gods abundant Grace at work from the beginning. Prior to the Mosaic law, those from Adam to this present day are not excused for the lack of the law as they had conscience and knowledge of good and evil as a result of Adams original sin.

 

[JacksBratt]

To your point of those who are incapable of understanding sin or right from wrong I will not argue and agree and thank you for pointing out those versus, which frankly, I would typically read over and not dwell on as they are part of a larger frame of reference in context of the over reaching point Paul was making in terms of Gods abundant Grace at work from the beginning. Prior to the Mosaic law, those from Adam to this present day are not excused for the lack of the law as they had conscience and knowledge of good and evil as a result of Adams original sin.

Was that not what started the whole thing... Not just the disobedience of eating a forbidden food.. but gaining the "knowledge" of good and evil... from then on... we were accountable.