How can I learn to distinguish right from wrong?

Romans 12:2. "And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect will of God." The connection between the first and second verses is manifest and beautiful. We have the body in the one and the mind in the other; the whole man is brought in. We are also reminded thereby, that mere bodily exercise, though consisting in the diligent observance of rites and ceremonies, would profit nothing without the renewal of the mind. The inner as well as the outer man must be formed morally for God, and His service. Hence the one grand end for the Christian to gain is the discernment of the will of God; and the highest expression of christian life in this world, is the life that is most perfectly subject to the divine will. We have to prove — though we may be long in doing so — that this and this only is good, acceptable, perfect, and well pleasing in His sight.

Since the divine instructions to us are that we be transformed by the renewing of our minds, we may well enquire how we may get our minds renewed. The answer is, by getting them formed according to God's thoughts and forsaking our own. And how shall this be? By soaking them in God's Word, which conveys to us God's thoughts. As we read and study the Word in prayerful dependence on the enlightening of the Spirit of God, our very thinking faculties, as well as our way of thinking, become renewed.

This figure is unfolded in the next two verses. In no way is milk slighted in its due place. It is the most wholesome and suited of all nourishment for the infant; but the grown man requires quite different food for his developed state and appropriate duties. "For every one that partaketh of milk [is] unskilled (or, without experience) in the word of righteousness, for he is an infant; but solid food belongeth to full-grown persons that have by reason of habit their senses exercised for distinguishing both good and evil." By "partaking" is meant having milk for one's share in ordinary use, as a babe takes it not for partial or occasional fare, as any one might. The word translated "full-grown" is literally "perfect," and given in the A.V. so repeatedly that some lose the true force, which is simply those come to maturity.

He prays for discernment (judgment). Sometimes this may signify a “spiritual sense of smell,” or “taste;” but here it has the sense of taste for judgment, discernment, reason. Paul prays for the Philippians in chapter one verse 10: “That ye may approve things that are excellent,” or as the N.I.V. puts it: “ … so that you may be able to discern what is best … ” For the believer it is not a question of refusing sin or sinful things, but of discerning what is profitable and constructive, and what is not. Good judgment and knowledge are essential for spiritual growth. “ … but solid food belongs to full-grown men, who, on account of habit, have their senses exercised for distinguishing both good and evil” (Heb. 5:14). Now this kind of spiritual discernment does not come to us automatically, as we learn from the verse in Hebrews 5. It comes with practise. That is why the writer begins this verse 66 with: “Teach me … ” Are we willing to be taught?

The Holy Spirit would Himself teach by the written word, those who when taught are to teach others. The Holy Spirit would equally aid the hearers in ascertaining whether, what is taught agrees with the revealed and inspired word of God. "Prove all things," says the apostle, "hold fast that which is good." Reject, of course, what is otherwise. Even in the case of apostolic teaching, those who heard were commended for comparing what was said with what had been already revealed and written, as we see in Acts 17:11, "These were more noble than those in Thessalonica, in that they received the word with all readiness of mind, and searched the Scriptures daily, whether those things were so." Never has there been a case of the Church usurping authority, either to teach, or to appoint those who are to teach, without grievous injury to souls, and what is worse, without contravening the authority of Christ, and hindering the sovereign action of the Holy Ghost. Nothing illustrates this more than the case of the Sacraments, utterly misplaced and perverted, to exalt the pretensions of a mere human priesthood. A multitude of collateral truths suffer through the attempt to maintain and justify this prime evil.

But on the other hand we are not to accept anything that is said without subjecting it to the test of the Word of God. We are to "prove all things." However, young in the faith, this was the personal responsibility of every saint. Nothing was to be taken for granted or taken merely on the word of another; Scripture was their one real authority. And what is good we are to hold fast, allowing nothing to slip of the precious truth of God. This too was essential if they were to "avoid every form of evil" U.N. Darby). For evil will assume most attractive and deceiving forms just as readily as more gross forms, and only the heart holding fast what is good will be protected.

Is it necessary that we should be informed of all the history of evils or of all the details of the workings of evil in order to be preserved from it? This word answers decisively. To have our souls filled with the good Word of God is our serious need — not occupied with discerning evil, but so occupied with good that any evil that may present itself may immediately be discerned and judged. “Wise unto that which is good” is a blessed word for our souls. Just as a bank teller is trained diligently in handling only good currency, in order that a spurious coin or bill would be immediately detected, so should our souls be well-trained in that which is good. Then the evil, whatever form it takes, would be discerned through its dissimilarity to the good.

Clearly it is not the will, for conscience frequently pushes its way in opposition to the will. Neither is it reason, for while a man's reason will demonstrate to him that a given course of action will work him injury, yet his conscience will impel him forwards to do the right thing, even to the wronging of himself. It is not a conclusion arrived at in the mind upon weighing over the right and wrong of a question. Conscience is the moral sense of right and wrong which is innate to man. It is as much a part of his present being as his reason or his will. We may describe conscience as the eye of man's moral being, or liken it to a voice within his breast commanding him concerning right and wrong.

Conscience is not a faculty in man, enabling him to know abstractedly what is right and wrong, but, given the law of right and wrong, conscience appeals to man according to the precepts of the law he knows. Conscience needs instructing, it does not instruct; and according as the conscience is faithfully instructed, so will its utterances be more or less just. In proportion as this eye is tutored will be the truthfulness of its perceptions.

Conscience is a natural thing, and came in with the fall in Eden; for, till then, all in man was right, and he could not think God had anything against His own unmarred handiwork — which man was. I notice conscience here because with it comes the question of honesty and uprightness, which are of great moment to the Christian. But if conscience is the knowledge which a man has before God, as to God's thoughts of this or of that, the unconverted man has no light of revelation in his soul; and the light which comes in at conversion makes everything manifest. A conscience must be, placed in the light and have the teaching of God ere it can rest satisfied that it knows what is right.

There is the knowledge of right and wrong as a faculty without God; but where God speaks, conscience is proved by bowing to it. See Saul: "I thought I ought to do many things contrary to the name of Jesus of Nazareth, which thing also I did." Acts 26:9. There was conscience. Once he has to do with the Lord, once he is right, it is "Lord, what wilt thou have me to do?" Acts 9:6, "Speak, Lord, for thy servant heareth." 1 Sam. 3:9. All short of this is alienation from God. A conscience that wants to be away from God, to judge for itself, is not an upright conscience. It is will and sin. Conscience is not only judgment, it recognizes the authority of God (we are sanctified to obedience) and loves it, because it is true conscience, and the will of independent self is given up, the soul restored to God. For the word has authority as well as light. It tests the truth of conscience by giving light, but it speaks with the authority of God. Hence the Lord says, The word that I speak unto you, the same shall judge you in the last day. Judge it now, if you dare. I do not believe in the conscientiousness of a man who pleads his conscience against the word of God.