Now we know that the law is good, if one uses it lawfully, understanding this, that the law is not laid down for the just but for the lawless and disobedient, for the ungodly and sinners, for the unholy and profane, for those who strike their fathers and mothers, for murderers, sexually immoral, men who practice homosexuality, enslavers,liars, perjurers, and whatever else is contrary to sound doctrine, 11 in accordance with the gospel of the glory of the blessed God with which I have been entrusted. 1 Timothy 1:8-11
St. Paul next proceeds to draw a catalogue of sins, against which the denunciations of the law are most eminently leveled; closing the list with the words first read, “And if there be any other thing that is contrary to sound doctrine.” A plain intimation, that error, in principles fundamental, has a very unfavorable influence on practicals: and that, in proportion as the doctrines of God are disbelieved, the commandments of God will be disobeyed. Doctrinals, therefore, are not of that small significance which the injudicious and the heterodox affect to give out. For, though matters of doctrine are, by some, considered merely as the shell of religion, and experience only as the kernel; yet let it be remembered that there is no coming at the kernel but through the shell: and, while the kernel gives value to the shell, the shell is the guardian of the kernel. Destroy that, and you injure this.
The apostle, in the words before us, stamps the evangelical doctrines with the seal of dignity, usefulness and importance: as is evident from the epithet he makes use of. He calls the system of gospel-truths sound doctrine: (didaskalia antikeitai) salutary, health-giving doctrine; not only right and sound in itself, but conducing to the spiritual strength and health of those that receive it: doctrine, that operates like some efficacious restorative on an exhausted constitution; that renders the sin-sick souls of men healthy, vigorous and thriving; that causes them, through the blessing of divine grace, to grow as the lily, and to cast forth the root as Lebanon, to revive as the corn, and to flourish as the vine, to diffuse their branches, and rival the olive tree (Hosea 14) both in beautyand fruitfulness. On the other hand, unsound doctrine has the very opposite effects. It impoverishes our views of God; withers our hopes; makes our our faith languid; blasts our spiritual enjoyments; and lays the axe to the very root of Christian obedience. We may say of it, as the Jewish students said, on another occasion, there is death in the pot. If you eat it you are poisoned. With the utmost attention, therefore, should we attend to the apostle’s caveat, and avoid every thing that is contrary to sound doctrine.Augustus Toplady: A Caveat Against Unsound Doctrine