If you do not experience discipline like everyone else, then you are illegitimate children and not true sons.
Here the apostle presses the exhortation to patience and perseverance by an argument taken from the gentle measure and gracious nature of those sufferings which the believing Hebrews endured in their Christian course. I. From the gentle and moderate degree and measure of their sufferings: You have not yet resisted unto blood, striving against sin, Heb 12:4. Observe, 1.
Commenting on Hebrews 12:4-17
But if ye be without chastisement,.... Or have no affliction: whereof all are partakers; that is, all the children of God; they are all alike children; they are all in a state of imperfection, and prone to sin; God has an impartial respect unto them: and though they are not all alike chastened, nor chastened at all times, yet none are exempted from chastisement, but...
Verse 8. But if ye be without chastisement. If you never meet with anything that is adapted to correct your faults, to subdue your temper, to chide your wanderings, it would prove that you were in the condition of illegitimate children--cast off and disregarded by their father. Whereof all are partakers. All who are the true children of God. Then are ye bastards, and not sons.