Placed in the position of this church, we might well have wondered about the purpose of the Old Testament law. The false teachers, who were just becoming visible as such within the church, were putting the Old Testament in a new light. It had a new kind of usefulness, if approached in the right way. Perhaps some who were not caught up in the trend noticed the increase in arguments over interpretation or how attention had shifted away from God and his demands toward human "knowledge."
In any case, Paul noticed it. He reminds the readers that the law is good if one uses it properly (v. 8). Some commentators understand this assessment of the law to contradict Paul's earlier views. In Romans 7:16 Paul said that the law, which intends life but provokes sin, is good. The demands of the law exceed our ability, and the knowledge of our sin that comes from these demands leads us to repentance. But, it is argued, this is not the meaning of 1 Timothy 1:8. Yet what Paul refers to here is the legitimate or appropriate use of the law, and there is in this a none-too-veiled glance at the heretics' misuse of it.
Verse 9 (law is made not for the righteous but for lawbreakers) amplifies "proper use": the purpose of the law was not to approve the conduct of righteous people, but to expose and condemn that of sinners. Against God's ethical standard revealed in the law, human sin stands out in bold relief. The heretics' interpretation of the Old Testament (used to support a gospel that promised too much too soon) obscured this revelation, so that sinners were no longer directed toward the genuine gospel. Their use of the Old Testament was illegitimate because it did not accord with God's purpose.
The list of sins in verses 10-11 is all-encompassing. The first three pairs (lawbreakers and rebels, the ungodly and sinful, the unholy and irreligious) introduce the range of sinful behavior, outward, inward and defiantly rebellious. What follows is a more specific catalog of the worst sort of sins which bears unmistakable resemblance to the Ten Commandments: those who kill their fathers or mothers (Ex 20:12: honor your father and your mother), murderers (Ex 20:13: you shall not murder), adulterers and perverts (Ex 20:14: you shall not commit adultery), slave traders (Ex 20:15: you shall not steal), liars and perjurers (Ex 20:16: you shall not give false testimony against your neighbor). The list concludes with the catchall whatever else is contrary to the sound doctrine--that is, the doctrine that bears the apostolic seal of approval.
In that final phrase Paul completes the statement of the purpose of the law: it reveals sins and sinners for what they are and points in the direction of the gospel. The false "teachers of the law" saw in the Old Testament law, especially in its "genealogies" (see above on v. 4) and creation stories, the basis for their extreme manner of behavior and the justification for their superspiritual claims. Their teaching missed the law's emphasis on God's demands and human need. False teachers are lawbreakers, who, without necessarily personally committing the sins listed here, become responsible for such sins by causing others to misunderstand or ignore God's moral demands.