If ye endure chastening, God dealeth with you as with sons; for what son is he whom the father chasteneth not?

Endure suffering as discipline; God is treating you as sons. For what son is not disciplined by his father?

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

If you do not experience discipline like everyone else, then you are illegitimate children and not true sons.