Matthew Henry speaks of conscience somewhere as, "the candle of the Lord which was not quite put out". Though it is not God's voice as such, the conscience, including the moral record in the heart and a man's mind or opinion, is a good gift from God. However, like every other good gift from God, the conscience has been affected by the Fall of man. George Washington spoke of the conscience as "that little spark of celestial fire" and the Puritan George Swinnock called it a "deputy deity in the little world man". Such expressions are acceptable as long as we remember that conscience is only a spark and the deputy is a fallible deputy at best.
Fallen
It has been denied by some but it is a fact that man had a conscience, that is a moral faculty, even before the Fall. The way Eve responded to the serpent by stating God's command concerning the tree of the knowledge of good and evil shows this. When Adam and Eve fell man fell. When man fell his conscience fell too. The Dutch theologian G C Berkouwer, in his work on the doctrine of man, rightly insists that any inclination to good characteristic of the conscience is:
dispelled by the reality of man's inclination to evil. .. We can never look to conscience as something which enables man to retain a relative goodness in a special organ standing outside the effects of corruption. (G C Berkouwer, Man: The Image of God, Eerdmans, 1962, p.170)
Similarly, the great Jonathan Edwards though he spoke of the natural conscience as being "as it were, in God's stead, as an internal Judge" yet he also argues very strongly in many places for the biblical doctrines of original sin and total depravity. In a sermon on Hosea 5:15 he says, Natural conscience remains, but sin, in a great degree, stupefies it, and hinders it in its work. (See Jonathan Edwards in Nature of True Virtue and On Original Sin and sermon, p. 61 in Select Works, Vol. 11, Banner of Truth Trust, 1958, quoted and summarised in REO White, The Changing Continuity of Christian Ethics 2 volumes. Paternoster Press, 1981, 2:259,260).
This is one reason why in the 19th century Scots holiness teacher Oswald Chambers, German Lutheran Franz Delitzsch, English doctor Alfred Schofield and others who wrote on the conscience all insisted that it is wrong to speak of conscience as the voice of God. Similarly, A H Strong, in his Systematic Theology, quotes D W Faunce approvingly, Conscience is not God - it is only part of one's self. To build up a religion about one's conscience as if it were God is only a refined selfishness. (A H Strong, Systematic Theology, Pickering & Inglis, 1962, reprint of 1907 edition, p. 501).
Chambers says "If conscience were the 'voice of God' it would be the most contradictory voice ever heard." To demonstrate this he instances the conscience of a Hindu mother and that of a Christian mother. (Oswald Chambers, Biblical Psychology, London, 1912, p. 217).
Schofield asserts that conscience is no more God's voice than the piano is Paderewski's voice. It will respond to a little girl's touch as much as to the master's. (A T Schofield, The Springs of Character, London, p 198).
Conscience is not the single virtue untainted by the Fall. Every faculty in every man is affected by the sin of our father Adam. We are separated from God. His image in man has been defaced, shattered. Just like all God's other gifts conscience is misused, abused and defective. This is true also of the record of God's requirements in our hearts (the moral record) and our capacity to think correctly (the mind).
The moral record
The mediaeval Roman Catholic scholar Aquinas spoke not of the moral record but of sunteresis or synderesis. The word was apparently first used by the Greek church father Origen to denote man's nature or the remnant of the image of God after the Fall. Aquinas held that this faculty, which supplied moral principles, was itself infallible. Later this idea was upheld by certain mystics but denied by the Jesuits who were happy to supply its place with their own rules. Although the term synderesis was used by the Puritans there was no suggestion that it was anything less than fallible. When Paul says in Romans 2:15 that the Gentiles have the requirements of God's Law written on their hearts he cannot be suggesting that each individual is born with an innate and thorough knowledge of God's Law. If that were so why would there have been any need for the revelation at Sinai? Paul is not holding up the very limited conformity of the Gentiles as a moral example. The point he is driving at, in fact, is that "there is none righteous, no not one" (Romans 3:10). As Professor John Murray points out in his commentary on Romans, Paul specifically states that it is the requirements of the Law that are written in men's hearts. (See John Murray, The Epistle of Paul to the Romans, New International Commentary on the New Testament, Eerdmans, 1955-65. In other words, everyone has some idea of right and wrong, but not a clear idea of God's holy law. Even if fallen man's conscience functioned perfectly it would not be bearing witness to a full and accurate record of God's commands. Thus in John Bunyan's classic, but lesser known allegory, The Holy War, we read that Mr Mind had only, "some old and rent and torn parchments of the law of good Shaddai in his house". (John Bunyan, The Holy War in Works, 3 volumes, Baker Book House, 1977 reprint of 1875 edition, first published 1682, 3:263) We should not be surprised, therefore, to find men not only excusing and defending themselves for things such as murder, idolatry and immorality contrary to God's Law; but also condemning themselves for eating meat or travelling in a car or missing mass, things not forbidden in the Law. Conscience itself is a witness not a lawmaker. It can only act on the evidence available and the known law.lt is like a skylight not a light bulb, a means of knowledge not a source. It refers us back to our own moral standard and urges us, with varying strength, to comply. If our moral record is faulty, proper obedience to God will be impossible. There are a number of contenders for the role of chief informant to the moral record. Tradition and trends vie with the truth. This is the reason sometimes for inward confusion and conflict. In his Bishop Sanderson Lectures, Christopher Wordsworth warns against following the example of men however learned or pious they may be. We must teach our consciences not to consider highest the opinions of others or even our own opinions as such but the Word of God.
Conscience proper
The conscience itself is also imperfect, of course. It is not useless, but it is unreliable. It can be variable, deceived, corrupted, intermittent or simply unable to cope with complex issues. Bunyan has Mr Conscience as the town recorder. After the fall of the town of Mansoul he would have terrible fits at times when he would "make the whole town of Mansoul shake with his voice" and yet at other times he would say nothing at all. (Bunyan 3:261) We can all identify with that state of affairs. Speaking of this element in conscience Oswald Chambers uses the illustration of what Ruskin called "innocence of sight". Artists are usually trained to paint what they see, not what they believe is there. The fallen conscience is like an untrained artist, it makes the mistake of not recording exactly what it sees. There is always a distortion.
The mind
Further, when conscience's faulty message is assessed in a man's thoughts he often suppresses it or finds other ways of ignoring it. In Holy War terms Mansoul becomes convinced that Mr Conscience is mad and not worth listening to. We see "the whole town in a rage and fury against the old gentleman". "Yea" says Bunyan "the rascal crew at some times would be for destroying him". (Bunyan 3:262) John 3:19-21 reminds us of the usual reaction of the fallen conscience.
God's spy
Everyone has a moral awareness. Anthropologists have failed to discover a totally amoral society. All realise there is right and there is wrong. The beginning of Paul's argument in his letter to the Romans makes clear that even unbelievers know there is a God, a God who will judge them concerning right and wrong. Therefore, even though the information available to the conscience is incomplete "the echo of the voice of God" does reach them. Jacques Ellul notes that, "The protests that indignity and injustice evoke from unbelievers as well as Christians indicate that the voice of conscience has not been utterly silenced and obliterated." (Ellul, quoted by P E Hughes, Christian Ethics in Secular Society, Baker Book House, 1983, p. 33).
It is important for believers to remember this. God has a "spy" in the hearts of unbelievers, what Thomas Brooks called "a preacher in the bosom". The conscience, however imperfectly, gives a man at least some idea of what God thinks of him and of his actions. Of course, the better informed a man's conscience the better the preaching; the more effective the espionage. This is why the unbeliever so often studiously avoids going to church or reading the Bible or having contact with Christians. He wants to "turn down the volume" or "do a deal" with his conscience. He will do almost anything to pacify it. We can almost always reckon on a man having a conscience that is active in some area. It is important for Christians to bear this in mind when witnessing to unbelievers. Where a man's conscience is relatively healthy we have an ally on the inside. As we bear witness to the truth from without, so does conscience within. Like Paul, we should aim to set forth the truth plainly, commending ourselves to every man's conscience in the sight of God (see 2 Corinthians 4:2). We seek to enlighten the conscience of the unbeliever with the lamp of God's Word.