Doctrine is a biblical truth or a set of biblical truths on a topic. Every biblical doctrine is God's will concerning a topic of faith or any matter of life. While Jesus taught, people "were astonished at his doctrine: for his word was with power" (Lk. 4:32; cf. Matt. 7:28; 22:33). Jesus then told them, "My doctrine is not mine, but his that sent me. If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself" (Jn. 7:16-17). The source of every biblical doctrine is God Himself. A biblical doctrine is divine truth that Christians ought to believe, or a divine will that Christians ought to obey.
Doctrine is not some sort of dull scholarly proposition, which are reserved for the intellectual elite of the church. Every Christian is to delight and abide in every biblical doctrine that God has revealed in His Word. The early Christians in Jerusalem "continued stedfastly in the apostles' doctrine" (Acts 2:42). All believers, new and matured, young and old, all were encouraged to delight in the biblical doctrines. In 2 Tim 3:14-15, we read, "But continue thou in the things which thou hast learned and hast been assured of, knowing of whom thou hast learned them; and that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus."
The LORD assures His people, "My doctrine shall drop as the rain, my speech shall distil as the dew, as the small rain upon the tender herb, and as the showers upon the grass" (Deuteronomy 32:2). God's doctrine is as “the rain” and “the dew”. What a depiction of beauty, goodness, graciousness and blessing! The doctrine's effect in a Christian’s life is like the rain and dew upon the tender herb.
By virtue of their faith, genuine Christians commit themselves to know and live by every teaching of God's Word. Jesus said, "If ye continue in my word, then are ye my disciples indeed; and ye shall know the truth, and the truth shall make you free" (John 8:31-32). Here, Jesus affirmed that the nature of true discipleship consists of continued obedience to His Word. In all matters of life, Christians ought to be guided by the sound doctrines of the Scriptures.
The Bible warns Christians not to live by worldly principles and patterns of life. From the time we believe in Christ, we should walk no longer as the unbelieving people walk. Ephesians 4:17–20 caution us that "ye henceforth walk not as other Gentiles walk, in the vanity of their mind, having the understanding darkened, being alienated from the life of God through the ignorance that is in them, because of the blindness of their heart: who being past feeling have given themselves over unto lasciviousness, to work all uncleanness with greediness. But ye have not so learned Christ" (cf. Rom. 12:2; 1 Pet. 4:3-4).
The thinking of the ungodly is contrary to God's truth. The reasoning and philosophy of the unregenerate people who live in their sins are contrary to sound doctrine (cf. 1 Tim. 1:9-10). Their minds are spiritually uninformed; hence their thinking is without the purposes and glory of God. Though their philosophies and principles could appear exciting and effective, Scripture warns us that they will eventually add more ungodliness, misery and wrath of God to one's life.
Prior to their regeneration, Christians lived according to the flesh – "…we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others" (Ephesians 2:3). While the unregenerate people live according to their evil passions (i.e. ungodly emotions and desires), Christians cease from living according to their lustful passions.
Like Christ lived on earth, every Christian "no longer should live the rest of his time in the flesh to the lusts of men, but to the will of God" (1 Peter 4:2). The Bible repeatedly exhorts Christians not to be driven by the lust of the flesh (cf. 2 Tim. 2:22; Tit 2:12). So, Christians are commanded to "put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof" (Romans 13:14).
Scripture warns against various doctrines that Christians must reject. They are doctrines of men (cf. Matt. 15:9; Mk. 7:7; Col. 2:22), doctrines of devils (cf. 1 Tim. 4:1; 1 Cor. 10:20; Col 2:18). Any doctrine that is deviant from biblical doctrine, according to Jeremiah 10:8, is "a doctrine of vanities". Instructions that distract believers from the truth of God is gross stupidity and folly, and will prove their adherents to be without understanding. Christians must, therefore, "be not carried about with divers and strange doctrines" (Heb. 13:9).
Scripture urges Christians, "In all things shewing thyself a pattern of good works: in doctrine shewing uncorruptness, gravity, sincerity,sound speech, that cannot be condemned; that he that is of the contrary part may be ashamed, having no evil thing to say of you” (Titus 2:7-8). Scripture says that all Christians must "adorn the doctrine of God our Saviour in all things" (Titus 2:10).
Christians must always conform to the truths of God’s Word. They must consider, “How do the doctrines of the Bible warn, rebuke and call to repentance? “How do they offer correction, instruction, hope, direction, restoration, etc?” If we truly take time to grapple with these questions, we will find doctrine to be most practical. Such practice of biblical doctrine will produce within us true piety and God-honouring lives.