What does the Bible say about self-harm / self-mutilation / cutting?

Body. The man tormented and injured himself physically. He gashed himself with stones. He had lost all the self-respect that nature itself teaches, wandering shamelessly in nakedness, finding shelter in the caves of the hillside, which were the sepulchres of the dead.

"Always, night and day, he was in the mountains and in the tombs," — utterly restless — "crying," — utterly miserable — "cutting himself with stones," — damaging himself in his madness. What a picture!

In Mark's account three main facts are specified about this man's state: — (1) He dwelt in the tombs; (2) He exercised superhuman strength, so that it was impossible to restrain him by fetters and chains; (3) He was a self-tormentor, inflicting injuries upon his own body.

Spirit. The highest part of human nature within him was dethroned. That "inspiration of the Almighty," the in-breathed spirit whereby man, as distinguished from the brutes, is capable of religious feeling, is shown to be debased also; so much so that there was an utter disregard for even the most ordinary and most easily-obeyed prohibitions of the law of Moses. According to that law in which without doubt he had been well instructed, even a momentary contact with that which was dead defiled (Num. 19:16). This man was so lacking in the feelings of an Israelite, as well as in those of a man, that he made his abode in the sepulchres. His spirit was in revolt against the divine will and paid no heed to the injunctions of God's word.

But the deplorable effects upon the Gadarene of his "possession" may be looked at in another way by viewing the maleficent influence of the demons from the five standpoints already named, the effects being practically identical, though differently arranged. This influence is shown by the Gospel narrative to be destructive (1) of the religious sense. By dwelling among the tombs, he cut himself off entirely from the worship of Jehovah as enjoined by the law. (2) of the sense of his duty to the laws of social and civil government. He would not, nor could not be restrained by chains or fetters, any more than by the love of home or of friends or of fellow-citizens. (3) of the sense of his duty to himself physically.He voluntarily injured himself, though he was responsible to care for the body as the servant of his higher nature. (4) of the sense of his duty to others. Instead of loving his neighbours, he was "exceeding fierce," and, like some ravening beast, terrified them by his savage aggressiveness. (5) of the sense of decency and propriety. "He wore no clothes" is the significant description of his appearance. The gloom of this picture is deepened by the fact that it was the manner of the man's life which is portrayed here. This was no sudden outbreak of evil passion, but the symptoms had been such for "a long while." They had become habitual. And he was wont night and day to express his forlorn and hopeless misery by loud, inarticulate cries.

And always, night and day, he was in the mountains, and in the tombs, crying, and cutting himself with stones." What a spectacle of utter misery! And even so, men are moral suicides. What more common than the expression, "He was an enemy to nobody except himself"? And though that is not true of any, for none can injure himself without injuring others, still it is ever true, that of all enemies, a man's worst one is himself. Indeed, without our own help, no enemy could injure us. Our fleshly lusts, our self-righteousness, our unbelief, with the thousand other evil growths that intertwine themselves with these, are our most real and deadly foes. And whether "in the mountains" of spiritual pride and self-sufficiency, or "in the tombs," the abodes of more palpable corruption, "crying, and cutting himself with stones" is still man's most constant occupation. It is a terrible picture, but a most true and lifelike one. Every "child of disobedience" is one in whom "the prince of the power of the air" thus "worketh."

Elijah gave the prophets of Baal plenty of time to call on their mystical god, crying, "0 Baal, hear us." When there was no answer, they jumped around the altar they had made, as though to influence their idol with their physical gyrations! After a few hours of useless energy, Elijah mocked them, telling them to cry out louder, for perhaps Baal was preoccupied or busy or on a journey or asleep, and must be awakened (v.27). They had no conception of an omniscient, omnipresent God.

These poor, deluded Baal worshipers evidently did not perceive Elijah's sarcasm, so they took his advice and cried out more loudly to Baal, also cutting themselves with knives and lances, Thus idolaters inflict injury to the flesh literally, thinking this is the self-denial that will influence their false god. How different indeed is the true self-denial of a believer! True self-denial makes no show, but involves a sober self-judgment in spiritual reality. The prophets of Baal continued this useless clamor all afternoon until the time of the evening sacrifice (v.29).

Verses 27-28 tell us that our bodies are not our own to do with them as we please, whether in shaving for show or making cuts in the flesh or being tattooed (Compare 1 Cor. 6:19-20). All of these are only to satisfy a person's pride.

Now, most evidently, it is God's prerogative to declare how His children ought to conduct themselves, and it is their high privilege and holy responsibility to seek, in all things, to meet His gracious approval. "Ye are the children of the Lord your God: ye shall not cut yourselves." They were not their own; they belonged to Him, and therefore they had no right to cut themselves or disfigure their faces for the dead. Nature, in its pride and self-will, might say, "Why may we not do like other people? What harm can there be in cutting ourselves, or making a baldness between our eyes? It is only an expression of grief, an affectionate tribute to our loved departed ones. Surely there can be nothing morally wrong in such a suited expression of sorrow!

To all this there was one simple but conclusive answer, "Ye are the children of the Lord your God" This fact altered everything. The poor ignorant and uncircumcised Gentiles around them might cut and disfigure themselves, inasmuch as they knew not God, and were not in relationship to Him. But as for Israel, they were on the high and holy ground of nearness to God, and this one fact was to give tone and character to all their habits. They were not called upon to adopt or refrain from any particular habit or custom, in order to be the children of God. This would be, as we say, beginning at the wrong end; but, being His children, they were to act as such.

"Thou art an holy people to the Lord thy God." He does not say, "Ye ought to be an holy people." How could they ever make themselves an holy people, or a peculiar people to Jehovah? Utterly impossible. If they were not His people, no effort of theirs could ever make them such. But God, in His sovereign grace, in pursuance of His covenant with their fathers, had made them His children, made them a peculiar people above all the nations that were upon the earth. Here was the solid foundation of Israel's moral edifice. All their habits and customs, all their doings and ways, their food and their clothing, what they did and what they did not do — all was to flow out of the one grand fact, with which they had no more to do than with their natural birth, namely, that they actually were the children of God, the people of His choice, the people of His own special possession.

This practice was forbidden in the law, as also was making any mark in the flesh. It was customary among the heathen, who cut themselves for the dead and tattooed their bodies in honour of their gods: the Israelites belonged to Jehovah. Lev. 19:28; Lev. 21:5.

On the subject of asceticism, any one having an ordinary acquaintance with scripture may see their ignorance of the mind of God, and their perversion of His word. We are exhorted, for example, to "mortify the deeds of the body," but never to mortify the body itself. The body is the Lord's, and to be cared for. "Know ye not," says the apostle, "that your bodies are the members of Christ?" True, they are to be kept under and brought into subjection, but that is the wisest way of caring for the body. (Rom. 8:13, 1 Cor. 6:15, 9:27) Again, the apostle says, "Mortify therefore your members which are upon the earth," and then he states what these are: "fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry." These are the deeds of the body which we are to mortify — to put to death practically; and this on the ground that the flesh was put to death on the cross. "They that are Christ's have crucified the flesh with the affections and lusts," not, observe are crucifying it, or ought to crucify it, but have crucified it. God has put it out of His sight by the cross, and we are to keep it out of sight by self-judgment. The body, on the contrary, has in the New Testament a most important place as the temple of the Holy Ghost, but the tendency of asceticism is to starve the body, and feed the flesh. "Which things have indeed a show of wisdom in will-worship, and humility, and neglecting of the body; not in any honour to the satisfying of the flesh." (Col. 2:23)