What does Proverbs 6:30 mean?

As with any "proverb," this is a general-case statement of wisdom. Even those who believe in law and order usually have sympathy for those who resort to theft when truly desperate. The book Les Misérables—later a famous stage musical—involves a character jailed as a child for stealing bread when starving. The story's message is partly founded in how most people sympathize with the motive behind such a crime, even if they don't think it should be left unaddressed. That need to balance compassion and justice is reflected in the following verse (Proverbs 6:31).

Even today, society often pities a desperately hungry person who shoplifts food items when destitute and starving. But now, even as in the ancient world, virtually no sympathy is offered to someone who steals his neighbor's spouse. The thief is still doing wrong, but at least others recognize his end goal was noble. The adulterer violates marriages to satisfy lust—both the ends and the means are corrupt. And adultery has a habit of inspiring other sins, such as lies or violence.

The adulterer doesn't satisfy his soul; he destroys it. He deliberately violates God's command, "You shall not commit adultery" (Exodus 20:14), and therefore he invites God's judgment. Only God's saving grace can erase the sin of adultery and restore the adulterer to favor with God. In 1 Corinthians 6:9–11, Paul reminds his readers that adulterers will not inherit the kingdom of God, but he recalls that some of them had been adulterers before God washed them from their sins.