Hebrews 12:8 But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons.

This passage further distinguishes the seperation of the two groups, discussed in verse 6. As stated in verse 6, all of God's adopted children are chastened, none are exempt. This passage describes the other group as "bastards", or rather fatherless. This unadopted group is not chastened in any form or fashion. Looking to Romans 8:7, this group, which is fully carnal, and under the power and authority of darkness, "is enmity against God: for it is not subject to the law of God, neither indeed can be". They have only a single carnal nature. God cannot chasten them, because they are not under His dominion or rule. This should not be understood as taking anything from His sovereignty. That would be an awful error. Instead, it should be understood, that in the same manner you are not responsible for the actions of the kids down the street, thier welfare, or thier learning, neither is God responsible for this group. Even if He did chasten them, they would not be able to comprehend, understand, or respond to what was happening.