Occasionally, when discussions of church discipline arise, some people worry that discipline might be applied to every kind of sin. If we discipline people who persist unrepentantly in adultery, does that mean that we should also discipline people for not giving faithfully, for not reading their Bibles and praying faithfully, for marital conflict, etc.? Where do we draw the line?
This is a very important question. I think Tom Schreiner, professor of New Testament interpretation at The Southern Baptist Theological Seminary, gives us a helpful answer.
His comments relate to 1 Corinthians 5:9-13, in which Paul says:
“ I wrote to you in my letter not to associate with sexually immoral people— not at all meaning the sexually immoral of this world, or the greedy [or covetous] and swindlers, or idolaters, since then you would need to go out of the world.  But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed [or covetousness], or is an idolater, reviler, drunkard, or swindler—not even to eat with such a one.  For what have I to do with judging outsiders? Is it not those inside the church whom you are to judge?  God judges those outside. ‘Purge the evil person from among you.’”
Commenting on this passage, Schreiner writes:
“Believers often ask which sins warrant discipline, particularly since all believers sin daily. Why should any distinctions be made among sins? Paul focuses, however, on sins that are publicly expressed and blatant. For instance, coveting, which is listed here, does not warrant public censure unless it expresses itself in extortion, embezzlement, or theft. In the same way virtually all believers struggle with lust. Believers who are fighting against lust are not to be excommunicated. When someone is struggling and fighting against sin, we help one another instead of excluding the one struggling from the church. But when lust expresses itself in sexual immorality and the offender does not repent of his sin, then discipline is necessary. Similarly, all believers sin in their speech. James, considering the speech of believers, says that ‘we all stumble in many ways’ (Jas 3:2). All believers need formative discipline, which includes reproof for sins of speech and a variety of other sins. Corrective discipline, however, is only necessary if one engages in slander and gossip and refuses to apologize or repent. Then the church must act to preserve its purity. The interpretation proposed here is supported by Titus 3:10: ‘Reject a divisive person after a first and second warning.’ We must discipline those who refuse to heed warnings – those who obstinately continue in their selfish behavior. If they do not submit after receiving warnings, then discipline must follow. So too, those who promulgate teachings contrary to the gospel and deny central teachings of the faith (the inspiration and authority of Scripture, the Trinity, the deity of Christ, justification by faith, etc.) and refuse to recant their teaching should be removed from the body.”
Tom Schreiner, “The Biblical Basis for Church Discipline,” Those who Must Give an Account: A Study of Church Membership and Church Discipline (Nashville, TN: B&H, 2012), 124.