Many people say that salvation is complete at the moment you believe in Jesus. If that is the case, what is the need for and value of doctrine?
Your doctrine is the belief system by which you make all decisions in your life, from whom you will marry to what you will do for a living to what you believe is right or wrong. God's Word speaks into all of these things and more.
Paul wrote to Timothy and gave instruction about doctrine. 1 Timothy 1:9-11 says that sound doctrine has to comform to the gospel. In 1 Timothy 4:15-16, Paul warns Timothy to persevere in his life and doctrine, and so save himself and his hearers.
Most valuable to this conversation is 2 Timothy 4:2-4, in which Paul warns that the day will come when men will not put up with sound doctrine. This fact comes up after Paul admonishes Timothy to rebuke, correct and encourage people with the Word of God.
Who will put up with rebuke or correction from the Scriptures anymore? The "wisdom" of the day is that we all sin, so no one has a right to correct or rebuke anyone. Is this the fulfillment of Paul's prophetic warning to Timothy coming to life in our day; in our church? In your church?
Doctrine. Does it matter? Is it extra-gospel rules, or intra-gospel necessity? Chuck Coleson wrote a book that asked the question, HOW THEN SHALL WE LIVE? I might ask my question this way: "WHY, THEN, SHOULD WE LIVE LIKE THAT?"