Christ has graciously given His church a system of discipline by which to protect His people and vindicate His glory
In Matthew 18 we can see the basic elements of church discipline, where Christ teaches that the sin of a brother who fails to heed two stages of admonitions is to be "told to the church." In this passage, Christ presupposes due process, that is, a forum in which evidence may be examined according to rules, witnesses cross-examined for competence and truthfulness, and the "charge" itself evaluated as to its relevance and importance. To deny that this passage presupposes certain minimal notions of due process would lead to the unacceptable alternative, that the Word of God invites believers to publish indiscriminate gossip and unsubstantiated allegations. If church discipline entails due process, then church discipline requires a church court. Apart from a church court, there is simply no way to carry out the command of our Lord in Matt.18.
The "brass tacks" involving all the practicalities entailed by the existence of a church court offends people who have a "spiritualized" notion of what the church should be like. But Almighty God often ordains very practical remedies such as church courts, and officers to operate such courts. When Jethro suggested to Moses the appointment of coregents, his concern was very likely pragmatic (Ex.18:13-15). Yet, in the providence of God, this solution took on the force of divine ordination by virtue of the fact that Moses, God's prophet, heeded the suggestion and appointed coregents (Ex.18:24-26). A similar (and specifically spiritual) pattern was ordained by God when the 70 "elders" were called into God's presence in a feast before the Lord on the mount (Ex. 24:9-11). At this feast, they, in a sense, represented the people before God; later, as judges, by virtue of their divine ordination, they represented God to the people. This representative, covenantal, and authoritative principle of organization continued with minor variations even up to the time of the NT in the synagogue and was re-ratified as it were, in the appointment by the apostles of elders in each congregation (Acts 14:23). So the requirement of setting aside men to be, at once, representatives of, and authorities over the congregation is established by the weight of both the Old and New Testaments (e.g. Acts 15:4,6,22,23; 20:17,28; 16:4).
The authority to guard the sacraments is moreover an inescapable concept inasmuch as this function must unavoidably be exercised. Even the most liberal church, after all, has some constituted authority which is able to set aside any restriction that could be placed on access to the sacraments. But Scripture is more explicit. After quoting Num.15:30,31 and especially Deut.17:12 ("The man that will do presumptuously, and will not hearken unto the priest that standeth to minister there before the Lord thy God, even that man shall die; and thou shalt put away the evil from Israel") Ursinus concludes:
From these two passages just quoted, it appears that God commanded such as were rebellious and wicked to be cut off from the Jewish commonwealth, and would not allow them to be received amongst the number of his people. Much less, therefore, would he allow them to be regarded as members of his visible church, and be admitted to her sacraments.
Jeremiah severely reproves those who had the boldness to come into the temple whilst they were still defiled with their sins. (Jer. 6:7,10,20.) Ezekiel declares that God will not be enquired of by those who go after strange gods, and then present themselves in his temple. (Ez. 20:31.) And, in the 20th verse of the same chapter, he says that those profane his sabbaths, and pollute his sanctuary, who come into his house defiled with their idols. The prophet Amos rejects the sacrifices and worship of wicked transgressors, saying, "I hate, I despise your feast-days, and I will not smell in you solemn assemblies." (Amos 5:21.) The prophet Haggai forbids (2:13,14) the unclean in soul to touch that which is holy, where he speaks of moral and ceremonial uncleanness... And, in Prov.15:8, it is declared that "the sacrifice of the wicked is an abomination to the Lord."By virtue of these behavioral demands, the church is to be a rather exclusive body. Indeed, the church fellowship is to demand, on pain of expulsion, a much higher standard for fellow believers than is held for unbelieving associates (I Cor. 5:9-10). The church must not tolerate overt evil in even a small measure, for "a little leaven leaveneth the whole lump" (I Cor. 5:6, in the very context of church discipline).
As regards the individual being expelled, Paul uses the most dire terminology imaginable when he commands, "Deliver such a one to Satan for the destruction of his flesh" (I Cor. 5:5). Even then, however, Paul has an eye on the restoration of the unruly one "that his spirit may be saved" (same verse). Paul presents a stark contrast which those outside the church will never be able to fathom: he instructs the Corinthians in such severe terms, yet he does so tearfully (II Cor. 2:4) and with the hope for restoration always of foremost concern (II Cor. 2:7-8).
There is first the distinction between behavior and belief. This distinction is summarized in the Westminster catechism, for example, in answering the question, "What do the Scriptures principally teach?" "The Scriptures principally teach what man is to believe concerning God, and what duty God requires of man." We may take this summary as dividing the jurisdictional scope of discipline between that which applies principally to the teachers and leaders of the church, and that which applies to all members without distinction. Whereas matters pertaining to "the duty God requires of man" applies to all men without distinction, the matters of "what man is to believe concerning God" applies, so far as discipline is concerned, most especially to the teaching leadership of the church. The latter are required to be "apt to teach" (I Tim. 3:2) as well as to gainsay error (Tit. 1:9), even among true believers who may struggle with this or that doctrinal point. Though worthy of a discussion in its own right, this essay does not address the special category of church discipline applicable to teachers.
The behavioral aspect of discipline, though, reveals a second important distinction. Discipline in the form of public censure is only one extreme of a continuum. It is important to bear this in mind since several passages deal with that gentle and continual admonition as the environment in which all believers are to submit to one another (Matt. 18:15; Gal. 6:1; Prov. 25:12; etc.) It is at this level that what we know as church discipline really begins. But beyond this responsibility of all believers to admonish one another, the shepherds, in discharging their solemn duty, have a positive obligation to warn all those in their care to repent of sin. Paul declares that his ministry was not only "public" but "house to house" (Acts 20:20) and that he diligently "ceased not to warn every one night and day with tears" (Acts 20:31). Because Paul took his responsibility to discipline the body seriously, he can say that he is "pure from the blood of all men" (Acts 20:26). The obligatory nature of the function of discipline for both shepherds and all believers is brought into sharp focus in Hebrews 13:17, which warns that the under-shepherds "watch for your souls, as they that must give account."
But, rebuke is proper only when it is based on the Word of God. Calvin explains the relation of these so-called "keys of the church" to the Word of God as follows:
This command concerning forgiving and retaining sins and that promise made to Peter concerning binding and loosing ought to be referred solely to the ministry of the Word, because when the Lord committed his ministry to the apostles, he also equipped them for the office of binding and loosing. For what is the sum total of the gospel except that we all, being slaves of sin and death, are released and freed through the redemption which is in Christ Jesus and that they who do not receive or acknowledge Christ as their liberator and redeemer are condemned and sentenced to eternal chains?...It was important for the apostles to have constant and perfect assurance in their preaching, which they were not only to carry out in infinite labors, cares, troubles and dangers, but at last to seal with their own blood....It was important for them to be convinced that in such anxiety, difficulty, and danger they were doing God's work; also, for them to recognize that God stood beside them while the whole world opposed and attacked them; for them, not having Christ the Author of their doctrine before their eyes on earth, to know that he, in heaven, confirms the truth of the doctrine which he had delivered to them. On the other hand, it was necessary to give an unmistakable witness to their hearers that the doctrine of the gospel was not the word of the apostles but of God himself; not a voice born on earth but one descended from heaven.... Accordingly, Christ has testified that the forgiveness of sins which they preached was the true promise of God; the damnation which they pronounced, the sure judgment of God. This testimony, moreover, was given to all ages, and remains firm, to make all men certain and sure that the word of the gospel, whatever man may preach it, is the very sentence of God, published at the supreme judgment seat, written in the Book of Life, ratified, firm and fixed, in heaven.Here, Calvin expounds the locus classicus of the keys of the church in a way that gives a satisfactory account of how the apostles, in their historical placement, might very well have reflected on the Lords' words. Calvin also grants the most awesome and solemn meaning to the exercise of the keys, yet without in any way allowing grounds for the tyrannical claim of self-authenticating power such as is made by Roman Catholics. The centrality of the ministry of the Word and the obedient hearing of the Word, precisely because it is the Word of God, is the point. The crux of church discipline, in which we can see its glorious beauty, is, therefore, the appeal to conscience in a manner that is displayed objectively. This idea will become more clear as we continue.
At the same time, it is evident that this relation is legally voluntary, in the sense that no group of elders, even granted that they have proper credentials, has the power to compel anyone to make the covenantal commitment required of them by Scripture.
The nature of subjection to church discipline as being at once voluntary (with respect to its physical constitution) and yet obligatory (with respect to the command of God) raises an interesting question: may one resign from this "voluntary association"? Clearly, resigning would seem to be a convenient way to escape the nuisance and potential embarrassment of facing charges in church court. In general, how should a tendered resignation be received by the church?
The question can perhaps be put in its most awkward form as follows: when a member, not in overt rebellion, but professing to have lost faith in God, tenders his resignation, not (apparently) to escape discipline, but to reflect honestly the change in the state of his own heart, should this resignation be accepted without further process by the session? It is assumed, of course, that much in the way of counsel and private exhortation would ensue, but given the persistence of the resigner, should the resignation simply and passively be accepted?
This question arose in the Presbyterian church in the nineteenth century in connection with the revision of the book of discipline. In 1857 a committee consisting of Charles Hodge in the north and James Henley Thornwell in the south, among other luminaries, was commissioned to prepare a new manual of discipline. This committee concluded that church membership was voluntary: accordingly, it held that one who resigned his membership on the grounds of unbelief should simply be "erased" from the rolls of the church, but without further ado other than perhaps announcement of the erasure. Thornwell wrote in defense of this position:
Every man has a right to withdraw from the Church whenever he pleases, in the sense explained in our former article -- a right in the sense that no human authority has the right to detain him. As before God, he has no more right to apostatize than to commit any other sin. He is bound to believe and keep the commandments. But men have no commission to force him to do either. If he wants to go, they must let him go. "They went out from us," says the Apostle -- not that they were expelled, but they went out of their own accord, freely, voluntarily -- "because they were not of us." They found themselves in the wrong place, and they left it.Thornwell was careful to define the "right" of defection, not as if the defector had such a right before God, but rather in the sense of the absence of any right to obstruct him in his defection. Note carefully, however, that Thornwell also excludes the case where offenses worthy of discipline have occurred. He focused on the case of a man who quietly and "unoffensively" renounces the faith and wishes peacefully to withdraw. Nevertheless, even in this tightly restricted case, Dabney, in responding to the proposed change took up the gauntlet in no uncertain terms:
"The attempt has been made several times in General Assemblies -- as in 1848 and 1851 -- to establish this most sweeping, mischievous and un-Presbyterian usage." Dabney's objections to Thornwell's view center chiefly on the following considerations. (1) The rule (allowing simple resignation) would in practice provide a ready escape-hatch for those in danger of being cited for sin, and effectively put an end to church discipline of any kind. (2) The rule is premised on a falsehood, namely, that unbelief is not a disciplinable sin. (3) Consequently, church sessions would be remiss before God in relinquishing their duty before God to exercise discipline on such grounds. (4) Moreover, there are only two kingdoms, that of Christ and that of Satan; dismissal from the church can only be to the kingdom of Satan, and (ironically) it would be overly harsh to so relegate a church member to the kingdom of Satan, or to absent the wholesome presence of the fatherly censures of the church, before outward behavior of a scandalous sort made it obligatory and necessary to do so.
Reading Dabney's arguments today makes it clear how far, in just a little over a century, even the conservative Reformed churches have departed from the standards of their forefathers. We are barely in a position to even follow the debates. Just one citation from the extended passage is presented to show how not just our practice but our very way of thinking about issues has radically shifted.
Are not avowed impenitence and unbelief incompatible with Christian character, and does not their tolerance in communicants "bring disgrace or scandal" on the Romish and other communions, which formally allow it, in the eyes of all enlightened men? They are, then, a disciplinable offence. But hear Paul (1 Cor 16:22), "If any man love not the Lord Jesus Christ, let him be Anathema Maranatha." Here we have the very formulary of excommunication pronounced, and it is against the man who "loves not the Lord Jesus Christ;" that is, just the man who, in modern phrase, avows himself as "lacking in the suitable qualifications for the Lord's supper."In dealing with this member who confesses to unbelief and wishes on those grounds to be released from the jurisdiction of church discipline, Dabney counsels extended, tender, and forbearing treatment on the part of the session, but with this difference from that proposed by the commission: "the session should do judicially, on the ground of his own avowal, what he had requested, except that they should debar him from the Lord's table until repentance, instead of giving him license to neglect it." 
The church, we hold, is solemnly bound to teach the same doctrine in her discipline which she preaches from her pulpits, otherwise she is an unscriptural church. She is bound to testify by her acts as well as her words, against the destructive and wicked delusion so prevalent in consequence of the wresting of the doctrines of grace, that because grace is sovereign, therefore, the failure to exercise gracious principles is rather man's misfortune than his fault. It is this dire delusion which hides from men the sinfulness of their hearts; it hath slain its ten thousands. With what consistency can the pulpit proclaim that unbelief is sin, and then send forth the same pastor into the session room to declare to the misguided transgressor, in the tenfold more impressive language of official acts, that it involves no censure, and that its bold avowal is rather creditable than blameworthy? Shall not the blood of souls be found on such a session?
Though it is far from my desire to adjudicate between such giants of the modern church as Dabney and Thornwell, it does appear that Dabney met Thornwell's basic objection and presented a solid Scriptural case, one which rings true to a sound understanding both of human nature and of the reformed understanding of the church. Yes, the church is a voluntary organization with respect to outward compulsion; but there are only two kingdoms, and only to its own peril will the church pretend that there is a principle of freedom which supersedes the lifelong obligation of all who profess entry into the kingdom of light.
With church discipline, then, the basic appeal is to the transgressor's conscience. By conscience we do not adopt the modern perverse sense of "take it or leave it as it appeals to me." By conscience we refer instead to the inner sense of one's standing before God in light of holy writ. The leaders of the church, fulfilling a commission from God Almighty Himself, solemnly pronounce judgment, as it were as a proleptic enactment of the judgment day itself, but with a glorious, gracious difference: there is still time for repentance! By providing a forum wider than our own private ruminations -- which, after all, are prone to be twisted, evasive, and self-deceptive -- church discipline affords a chance to be examined and to "make it right" in the sight of God. Thus, we should all view church discipline as a tremendous blessing.
Because church discipline relates directly to one's standing before God, there is no room for evasion or dissimulation. Just as there will be no room for evasive tactics on that Great Day at the end of history -- no finger pointing, no self-righteous assertion "you can't prove that from the words I used" -- so one should not attempt to evade responsibility in the church court by such tactics. In a very real sense, one stands immediately before God in the church court, and as such, those who stand before the court should diligently adjust their attitudes accordingly.
Although church courts, unlike civil courts, do not employ physical coercion, ironically, church courts place a far more rigorous demand than that required of him in the civil court. If, for example, I am brought to court for a speeding violation, I am not obligated to confess to all the times I have exceeded the speed limit but for which I have not been caught. In order to ensure that justice is meted out fairly, there is a sense in which it is the state's responsibility to build up its own case, and not seek confessions. Indeed, state-extracted confessions have often been the seedbed for tyrannous regimes to follow. I may present any lawful argument in favor of extenuating circumstances and lenient treatment, and even hire a lawyer to do the same more skillfully. In the church court, on the other hand, it is a privilege and not a disadvantage to have one's motives cross-examined in the context of getting right with God. Excuses are out of the question. If I am being examined because of fornication, it would be highly appropriate to mention any personal history of a struggle with lust: the more sins that can be straightened out, the better!
For those that have not caught sight of the glorious beauty of church discipline, fearfulness is often the main obstacle. The fearful one must ask himself, however, what the real object of his fear is. Is the worried look of one, the furrowed brow of another, the imploring expression of still another, something to strike terror into one's soul? One should ask himself whether his fear is not rather the fear of having sin exposed which was comfortably hushed up and tucked away in the privacy of his heart. Fear in this sense is sin. Overcoming such sinful fear is necessary in order for the believer to stand before God with a clear conscience. This comes near to the essence of godliness.
Indeed, the practical effect of church discipline, rightly applied, is so beneficial, that if anything, the temptation might be to seek it out: to apply to be examined before the church court routinely. But there are at least two reasons why such a response would be wrong. First, such an orientation would tend toward narcissism. The goal of sanctification should be first and foremost keeping one's eyes on Christ, and not even on my own puny residual wickedness. Second, such a desire could be an unconscious disguise for self-righteousness, in that the hope for vindication before the examination of the church court could be confused with actual righteousness before God.
A number of practical issues have been left untouched here: for example, the biblical rules of evidence and why these are important; the times when appeal of a judgment is proper; the problem of personal animosities thwarting the true goal of discipline, etc. I have tried to show that church discipline is Biblically required, and like all Biblical requirements once understood, is not only an obligation, but a thing of great beauty.
 Such an alternative is so unacceptable that it scarcely seems necessary to mention that it would violate numerous Scripture passages, as "he that is of a faithful spirit concealeth the matter" (Prov.11:13b); "thou shalt not go up and down as a talebearer among thy people...I am the Lord" (Lev.19:16); "...tattlers also and busybodies, speaking things which they ought not" (I Tim.5:13), etc.
 Following G.Gillespie, Aaron's Rod Blossoming (Sprinkle Reprint) p. 5, we recognize that the elders of Ex.24 were a different group from the leaders put in office in Ex. 18.
 Ibid. pp. 4-15; cf.also R.L.Dabney, Discussions, vol. 2, "Theories of the Eldership," pp. 128ff.
 The commentary of Dr. Zacharias Ursinus on the Heidelberg Catechism, trans. G.W.Williard, (1852) Presbyterian & Reformed: Phillipsburg (no date) pp. 442-443 (comments to question 83).
 Z.Ursinus, op.cit. p. 443
 Westminster Larger Catechism question #6; Shorter #3.
 Paul Stookey in his "Wedding Song" is only one of the more well-known cases of those who imagine they can lay claim to this verse.
 Calvin, Inst. IV.11.1 (pp. 1212-1213 Westminster Press edition).
 On the very recently reaffirmed continuation of autarchy in the Roman Catholic Church, see T.Schirrmacher "Has the Roman Catholic Church Changed?" Antithesis, Vol. I, No. 2 (Mar/Apr 1990) pp. 23-30.
 Resignation is of course to be distinguished from a proper transfer.
 "Session" is used here to refer to the duly-constituted panel of church leaders which render judgment in church discipline cases. In non-Presbyterian circles this panel may be referred to by other names, such as "consistory."
 The exact text goes as follows: "In cases in which a communicating member of the church shall state in open court that he is persuaded in conscience that he is not converted, and has no right to come to the table of the Lord, and desired to withdraw from the communion of the church; if he has committed no offence which requires process, his name shall be stricken from the roll of communicants, and the fact, if deemed expedient, published in the congregation of which he is a member." Cited by R.L.Dabney, Discussions, Vol.II, p. 332.
 The Collected Writings of James Henley Thornwell, Vol.4: Ecclesiastical, p. 370.
 "The right of a man to do a thing, and the right of others to hinder him, are entirely distinct, and yet, from the poverty of language, we are often compelled to represent the non-right of others to hinder as his right to do" Ibid. p. 324.
 "The injury they have done to [the church's] name and character they are as much bound to answer for as any other offenders, and they are not to be at liberty to plead the right of withdrawal as a cover for their crimes." Ibid. p. 371.
 R.L.Dabney, Discussions
 Ibid. 332-339
 Ibid. p. 336
 Ibid. p. 338
 Thornwell's view however can hardly be cited by moderns in their defense: "The man is treated as an offender...the guilty party is solemnly, and by the sentence of a court of Jesus Christ, excluded from the fellowship of the saints, because the love of God is not in him. The sentence, too, is an awful one, the most awful that can be pronounced on earth save that of excommunication." Collected Writings, p.325.
 Except in the sense that access to the table might have to be physically blocked, if it came to that.