“knowing this, that the law is not made for a righteous man, but for the lawless and disobedient, for the ungodly and for sinners, for unholy and profane, for murderers of fathers and murderers of mothers, for manslayers, for whoremongers, for them that defile themselves with mankind, for menstealers, for liars, for perjured persons, and if there be any other thing that is contrary to sound doctrine; according to the glorious gospel of the blessed God, which was committed to my trust.” (1 Timothy 1:9–11)
Notice that the apostle tells the young preacher that sound (hygienic) doctrine has behavior that corresponds to it. Doctrine is essential in the church. We are to give heed to it in our preaching (1 Timothy 4:16), and our preaching should be full of it (2 Timothy 4:1-3).
Doctrine alone is not what we need, however. Doctrine should lead to practice. This is why we read that the Scriptures are profitable for doctrine, for the purpose of changing our hearts, minds, and behavior and making us the people God wants us to be.
Paul told Titus that the doctrine of God has a lifestyle that goes along with it, and that sound doctrine should be like clothing for us (Titus 2:1-15).
Brothers, we cannot neglect doctrine because we think it is impractical. All sound doctrine is ordained by God to lead to sound minds and sound behavior, and we neglect it to our own peril.