In this regard there are unchanging positive calls to preach the Word (2 Tim. 4:1-2), to teach the whole counsel of God (Acts 20:27), to hold fast to the gospel (1 Cor. 15:1-2), to follow the pattern of sound words (2 Tim. 1:13; 1 Tim. 4:6), to guard the good deposit (2 Tim. 1:14; 1 Tim. 6:20), to appoint faithful men able to teach others also (2 Tim. 2:2), and to teach disciples all that Jesus has commanded them to obey (Matt. 28:19-20).
These imperatives set the tone and direction of Christian ministry. They call for a wholehearted commitment to love the Lord our God, to be faithful stewards of the gospel, and to feed his sheep (Jer. 3:15; 1 Cor. 4:1-2; Titus 1:9; 1 Peter 5:2).
Alongside these positive calls are the unrelenting warnings about the presence of false teachers, and clear instructions about how to deal with them (Rom. 16:17-18; Eph. 4:14; 1 Tim. 1:3-4; 2 Tim. 2:16, 22-26; Titus 1:11; 3:9-11; 2 Peter 2:1-3). These warnings are clothed in powerful images. False teachers are wolves, dogs, waterless clouds, fruitless trees, wild waves, wandering stars, and their teaching will eat up like gangrene (Matt. 7:15-20; Acts 20:29; Phil. 3:2; 2 Tim. 2:17; Jude 12-13) .
It is required of church leaders that they keep a watch on themselves, their teaching, and the flock entrusted to their care (Acts 20:28, 31; 1 Tim. 4:16). They must have a solid grasp of sound doctrine, held with a clear conscience, and an ability to mix it with false teachers (1 Tim. 1:5, 19; Titus 1:9). Truth must be taught and those in error must be rebuked and their teaching refuted.
Scripture never soft pedals the true nature and effects of heresy. It regards the most virulent forms of error as soul destroying and insidiously evil (Gal. 1:6-9; 2 Cor. 11:1-4, 12-15; 1 Tim. 4:1-3; 2 Tim. 2:25-26; 1 John 2:22; 4:3; 2 John 7). Harold O. J. Brown underlined the seriousness of rejecting the true gospel and embracing a different one:
...just as there are doctrines that are true, and that can bring salvation, there are those that are false, so false that they can spell eternal damnation for those who have the misfortune to be entrapped by them.
Nevertheless, in God's providence, these errors have been the occasion of producing greater clarity in the articulation of the essential articles of the Christian faith. They have also provoked some of the most substantial responses to be found in the theological literature of the Church. Alfred North Whitehead, of all people, rightly remarked that “wherever there is a creed, there is a heretic round the corner or in his grave.”
Rather more positively, Martin Luther was right to say that “If heresies and offenses come, Christendom will only profit thereby, for they make Christians to read diligently the Holy Writ and ponder the same with industry...Thus through heretics and offenses we are kept alert and stouthearted and amid wrangles and battles understand God's word better than before.”