When saving grace enters our lives we at once become concerned for our souls. This is what Solomon means when he states: 'A wise man's heart is at his right hand; but a fool's heart at his left' (Eccles. 10:2). The unconverted man does not see the importance of his own soul. He uses his right hand to grasp for the world and its pleasures. The things which relate to his soul are left to his 'left hand'. This is because he does not consider them important enough to engage his main energies in life. The things of the world are what his heart loves, whereas the things of God are to him remote and far off: grace, salvation, heaven, Christ and glory. 'Who that can enjoy the world now could be much interested in God or in future glory?' So says the graceless man.

All this alters at once when the grace of God enters the heart. Immediately and increasingly, once we are converted, we put the things of God first in life. Our priorities become those of the Bible. We take seriously what before seemed to us to be extremism. The man with faith knows now what Christ meant when He said: 'For what is a man profited, if he shall gain the whole world, and lose his own soul? Or what shall a man give in exchange for his soul?' (Matt. 16:26). Grace in the soul is 'oil in the vessel with our lamps' (Matt. 25:3). Grace in the soul gives us eyes to see and ears to hear (Mark 4:12). The soul that is renewed by grace sees the 'things that are invisible' (Heb. 11:1) and so recognizes the Bible to be the only light we have on the invisible world of God's kingdom. Grace gives us a single eye which is 'full of light' (Luke 11:34). No other power can give us this spiritual light but only the regenerating power of God's grace in the gospel. This alone teaches us the real value of truth, of the soul and of things which are eternal.

Truth and sound doctrine are what the renewed soul must feed on if it is to thrive, grow and be vigorous. That indeed is why the Word of God describes good doctrine as 'sound'. It is 'healthy' for the soul, just as wholesome food is beneficial to the body. Truth feeds the soul, strengthens the understanding and matures the graces of faith, hope and love. As the health of the body depends on the food we eat, so the vigour of the soul is profoundly affected by the preaching we listen to.

The first concern we should have in all our acts of worship is to hear only what is sound and good doctrine. This most certainly was the overwhelming concern of the New Testament apostles. Paul informs the young evangelist Timothy that he is to 'charge some that they teach no other doctrine' (1 Tim. 1:3). The Spirit's express warning, says Paul, was that, in these latter times of the New Testament, 'some shall depart from the faith' (1 Tim. 4:1). They would introduce into the pulpits of the church of Christ what he calls 'doctrines of devils' (1 Tim. 4:1). On the other hand the true minister is one who is 'nourished up in the words of faith and of good doctrine' (1 Tim. 4:6). The preacher to be praised and copied is the one who gives 'attendance ... to doctrine' (1 Tim. 4:13). He is told also to 'Take heed ... unto the doctrine' (1 Tim. 4:16).

The preacher who preaches any other than sound doctrine does so because he is 'proud, knowing nothing' (1 Tim. 6:3-4). False doctrine has its origin in human pride. A proud preacher is a servant of the devil. Being unregenerate he has no personal knowledge of God. His preaching aims at his own personal reputation. It invariably stirs up 'envy, strife, railings, evil surmisings, perverse disputings' and unedifying controversies (1 Tim. 6:4­5). The gospel preacher, therefore, must not be tempted to accommodate his message to suit human speculation or give way to 'oppositions of science falsely so called' (1 Tim. 6:20).

This emphasis on sound doctrine is found everywhere in the writings of the Apostle Paul, especially in his Pastoral Letters. The preacher who does good to souls is the one who holds 'fast the form of sound words' (2 Tim. 1:13). Only they are to be allowed in pulpits who are known to be 'faithful men' (2 Tim. 2:2). What this means is explained in these words: 'rightly dividing the word of truth' (2 Tim. 2:15).

Sound doctrine is the theology which flows from the accurate and proper exposition of the holy Scriptures. Really edifying preaching exists only where the apostolic attitude to the Bible exists: 'All Scripture is given by inspiration of God' (2 Tim. 3:16). The really called preacher is the one who holds 'fast the faithful word as he has been taught, that he may be able by sound doctrine both to exhort and to convince the gainsayers' (Titus 1:9). The Apostle never tires of bringing us back to the supreme importance of 'sound doctrine' (Titus 2:1), 'sound speech' (2:8) and the 'faithful sayings', which he instructed younger preachers to 'affirm constantly' (Titus 3:8).

The exact same concern is to be found in the other New Testament writers. Those who are not convinced should study 2 Peter chapter 2 and the Epistle of Jude. In both Epistles, there are fearful denunciations against all who bring false teaching into Christ's church or teach God's people to be carnal. They are, says Peter, 'wells without water, clouds that are carried with a tempest; to whom the mist of darkness is reserved for ever' (2 Pet. 2:17). They are, says Jude, 'clouds without water, carried about of winds; trees whose fruit withereth, without fruit, twice dead, plucked up by the roots; raging waves of the sea, foaming out their own shame; wandering stars, to whom is reserved the blackness of darkness, forever' (Jude 12,­13). Such implied imprecations are not the product of unsanctified clerical jealousy but the outpourings of pure and holy indignation, fully inspired by the Holy Spirit.

Nothing short of the highest and most momentous spiritual principles would ever induce these apostolic men to use such vehement denunciations as the above. That they spoke so strongly against those who preach error is evidence enough that unsound teachings are most damaging and hurtful to the souls of those who hear them. This indeed is what our Lord and his apostles, to say nothing of the Old Testament prophets, everywhere teach and affirm.

What do Christ and his apostles, in fact, say about teachers of error and about the effect of their error on men's souls? 'Beware of false prophets', says Christ, 'which come to you in sheep's clothing, but inwardly they are ravening wolves' (Matt. 7:15). Teachers of false doctrine, clearly, may be expected to come to us with every appearance of being genuine. Their falsehoods are 'clothed', like their persons, with much outward show of learning and scholarship. Their errors are concealed under doctoral degrees, perhaps, or cloaked under impressive titles of 'Reverend' and 'Very Reverend', adorned with much show of Oxford and Cambridge, Yale, Princeton and Harvard. They are strong on gowns, cloaks and starched collars but are most deficient in any personal knowledge of God in Christ, and have no love of an inspired and inerrant Bible. They have not drunk at the fountain of Truth nor do they aim at the good of souls nor the glory of God but rather at their own aggrandisement.

Those who want to see what Christ, the only Head of the Christian church, thinks of unsound practices should study Matthew 15 and Matthew 23. These two chapters are an epitome of Christ's opinion of unorthodox clergymen. 'They be blind leaders of the blind. And if the blind lead the blind, both shall fall into the ditch' (Matt. 15:14).

These words ought to be written in letters as red as blood over the classrooms of theological colleges of every kind. These words of warning should be hanging over the fireplace of every preacher's study.

Let every preacher repeat them to himself often: 'Into the ditch'. It is that deep pit into which all who teach lies will be cast along with all who believe their lies. How many myriads of clergy and laity – alas! – are there already!

Matthew 23 is Christ's uniquely full and detailed exposure of the corruptions of false clergymen and their doctrine. Is there anywhere a chapter like it in the whole Bible? 'Woe unto you!', 'Hypocrites!', 'Ye fools and blind!', 'Ye blind guides!', 'How can ye escape the damnation of hell?'. What searing, scorching, blistering, wounding words to all false preachers and teachers! And that too from the lips of One who is pure love, grace and truth! Oh, how such a chapter should be a warning to all who pretend to be ministers of Christ, yet have 'private reservations' about the church's Creeds and Confessions! What an alarm these words of Christ should be to any who imagine they are at liberty to add to God's written Word, or else to subtract from it (Rev. 22:18-19)! No wonder Paul, notwithstanding his great revelations, gifts and ecstatic experiences could say, 'Woe is me if I preach not the gospel' (1 Cor. 9:16).

But why should Christ and his apostles be so outspoken in their denunciation of bad preachers? Why did they denounce them with the strongest language found in the Bible? Why such thundering condemnation of preachers who may be in other respects likeable, even charming – men with good degrees and from good families – men whose only offence is that they do not preach the doctrines of the Bible?

The answer is inescapable: To preach anything but the doctrines of the Bible is to poison and to damn men's souls. All preaching which departs from sound doctrine is pernicious to the hearer, be it never so eloquent and never so learned in its presentation. The Apostle puts it succinctly in one statement of vivid intensity: 'Their word will eat as doth a canker' (2 Tim. 2:17).

We in our generation may find it difficult to identify with some of the metaphors of God's Word. After all, do we not like to think that we live in a sophisticated modern world? But here if anywhere is a metaphor we can readily grasp – eat like a canker (or cancer). Today every second person seems to be afflicted with cancer. This is a modern metaphor indeed!

The real problem with false doctrine is that it spreads through churches and nations just as cancer does. What can the Apostle mean? Just this, that what cancer is to the body, error is to the soul. It enters the soul through the eye and ear and silently spreads to all the faculties. It deadens the conscience till men have no sense of the sinfulness of sin. It spreads through the mind till it overspreads it with unbelief and clouds it with doubt. Its tentacles reach to the affections till they become dead to holy emotions and spiritual joys.

As cancer is the 'silent killer', so in a far more serious way is this spiritual cancer. It reduces a once-professing Christian to a confident agnostic. It transforms an evangelical preacher into a lover of lust. It drags down a once-respected Bible scholar to being a sacramentarian.

Even when it reaches into a probably regenerate soul it is able to do great mischief. It can 'eat' the heart out of a man's religion so that he becomes a mere shadow of his former self. He was once on fire for Christ; now he is hardly able to get to church once in a week. The Bible is laid aside; the newspaper and television are where his heart now appears to be. He formerly had family worship morning and evening in the home; now he scarcely says the 'Grace' before his food. The cancer of false theology has eaten deep into his soul.

The pulpit, if only we knew it, rules the world. It leads men and nations either to heaven or else to hell. The world is largely what it is because the pulpits are what they are. The cancer cannot be arrested by anything but a return to the Truth.