What does Hebrews 12:8 mean?

Here, the writer presents the alternative of discipline coming from a loving father: no discipline at all. In prior verses, heroes of the faith were said to have endured all sorts of worldly trials (Hebrews 11:35–38). Jesus, in particular, suffered despite being sinless (Hebrews 4:15) and still maintained belief that God would work all things out for future joys (Hebrews 12:2–3).

Here, the writer points out that a loving father disciplines, or trains, his children. It stands to reason, then, that those who don't experience any form of "discipline" are the equivalent to an illegitimate child. Note, carefully, that suffering the natural consequences of our sins is not the same as being disciplined by God. The context here is complex and easy to misunderstand. Many misinterpret this verse to mean that those who do not suffer some "minimum" level of persecution are not actually saved, but this is not the author's point. Recent verses specifically noted that the Christians to whom this letter was written had not endured nearly as much suffering as those who came before (Hebrews 12:4).

Earlier, the writer indicated that those who know God's will, but choose to disobey anyway, are subject to dire punishment (Hebrews 10:26–27). This is meant to be contrasted with the "discipline" suffered by those whom God is treating as sons and daughters. Those who take on the attitude of Jesus—that earthly hardships are God's way of preparing us for the future—are being "disciplined," as sons. The meaning and expectation of those trials is very different from those who suffer for the sake of their own disobedience. In prior passages, disobedience was linked to a loss of "inheritance" (Hebrews 6:11–12), again implying that God takes a fatherly stance towards His children. Later, this imagery will be mentioned again, in reference to Esau (Hebrews 12:17).

In short, those who are saved can expect to experience God's discipline. At the very least, this means enduring God's "chastening" through conviction when we sin. Those who profess to have faith in Christ, but experience no "discipline" of any kind when they sin—in particular a sense of conviction—are exhibiting signs of being "illegitimate children."

Further, this verse goes to support the idea that the warnings given earlier in Hebrews are directed at saved Christians. When we go astray, our loving Father correct us with some form of discipline. In extreme cases, this might result in drastic measures taken by God, in an effort to correct or block our path (Hebrews 6:7–8).