8 If you are not disciplined—and everyone undergoes discipline—then you are not legitimate, not true sons and daughters at all.

Read Hebrews 12:8 Using Other Translations

But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons.
If you are left without discipline, in which all have participated, then you are illegitimate children and not sons.
If God doesn’t discipline you as he does all of his children, it means that you are illegitimate and are not really his children at all.