Chastisement is a scourge (or punishment) against "Christian" unholiness and immorality. The scripture says in 2 Pet 1:4 that a real believer has "escaped the corruption that is in the world through lust". This selfsame scripture reasons that Christians DO NOT have a sin-nature but a 'divine nature'. Therefore, in favor of this perfect context, sin is nothing less than a gross anomaly for a real Christian -- in other words, sin is NOT normal for a real Christian. Of course, it is possible for a real Christian to sin, but it is possible for a real Christian NOT to sin. It is your choice!
Therefore, IF (not when) a real Christian sins, God will chasten him into a renewed state of holiness according to Heb 12:10; and so God in this way acts as his advocate (1 John2:1). If a professor of Christianity sins without respective chastisement, then he only proves himself to be a 'bastard' and not a real 'son' according to Heb 12:8. In conclusion, follow after holiness, without which no man shall see the Lord (Heb 12:14).