Within Christianity, there tend to be three major views of the place of excommunication:
1) We shouldn’t excommunicate anyone, because it’s not merciful.
2) We should excommunicate, because we want to purify the Church of the damned.
3) We should excommunicate, because it’s merciful to sinners.
So which of these views is the one endorsed by Scripture?
Number three. In fact, the first two are rejected outright within the Bible itself.
To those who fall into the first camp, who reject the place of excommunication within New Testament Christianity, I would point you to Jesus’ words in Matthew 18:15-18,
“If your brother sins against you, go and tell him his fault, between you and him alone. If he listens to you, you have gained your brother. But if he does not listen, take one or two others along with you, that every word may be confirmed by the evidence of two or three witnesses.
“If he refuses to listen to them, tell it to the church; and if he refuses to listen even to the church, let him be to you as a Gentile and a tax collector. Truly, I say to you, whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.”
Jesus is solemnly entrusting the Church with the power to bind and loosen, and this is closely tied with the Church’s ability to excommunicate unrepentant sinners.
And it’s more than just an ability. Jesus actually instructs it as the appropriate course of action to be taken in the case of certain unrepentant sinners. They are be ostracized, in the way that the Jews of the time treated Gentiles and tax collectors.
St. Paul, writing in Romans 16:17, similarly instructs: “I appeal to you, brethren, to take note of those who create dissensions and difficulties, in opposition to the doctrine which you have been taught; avoid them.”
So excommunication is Biblical, but it’s easy to understand why some people are uncomfortable with it, and find it contrary to mercy. After all, some of the noisiest defenders of excommunication defend it for the wrong reasons. As Rex Edwards of Columbia Union College wrote back in 1976:
“EXCOMMUNICATION has been regarded by ecclesiastics as the ultimate disciplinary measure. As a ‘weapon’ it has been conspicuous for its abuse. It has been employed as a penalty, often plunging the defendent [sic] into a situation of abysmal irreversibility.
“Luther in his ‘Discussion of Confession’ emphasizes the punitive aspect of excommunication, while Calvin declares it to be a public ecclesiastical censure for the purpose of purification.”
But excommunication isn’t treated as punitive in Scripture, and the idea that we are the ones who will purify the Church is actually an idea condemned by Jesus in Matthew 13:24-29,
“Another parable he put before them, saying, “The kingdom of heaven may be compared to a man who sowed good seed in his field; but while men were sleeping, his enemy came and sowed weeds among the wheat, and went away. So when the plants came up and bore grain, then the weeds appeared also. And the servants of the householder came and said to him, ‘Sir, did you not sow good seed in your field? How then has it weeds?’
“He said to them, ‘An enemy has done this.’ The servants said to him, ‘Then do you want us to go and gather them?’ But he said, ‘No; lest in gathering the weeds you root up the wheat along with them. Let both grow together until the harvest; and at harvest time I will tell the reapers, Gather the weeds first and bind them in bundles to be burned, but gather the wheat into my barn.'””
So the servants of the Lord want to go and try to purify His Kingdom by separating out the wicked from the righteous, but Jesus stops them from doing so, since their attempts to do so would surely result in unjustly condemning the righteous. Instead, He tells them to let the weeds grow alongside the wheat until the harvest.
When the Disciples ask what this means, He explains:
“Just as the weeds are gathered and burned with fire, so will it be at the close of the age. The Son of man will send his angels, and they will gather out of his kingdom all causes of sin and all evildoers, and throw them into the furnace of fire; there men will weep and gnash their teeth. Then the righteous will shine like the sun in the kingdom of their Father. He who has ears, let him hear.” (Mt. 13.40-43)
So it’s the job of the angels, not us, to purify the Church. And they’re going to do it at the Last Judgment, not now. In other words, the entire Protestant attempt to create a holy Church by creating a Church of only the righteous, of only the saved, failed from the start because Christ told them not to do it.
All of this is to say that creating a “wheat-only” Church isn’t why we excommunicate. And yet, we are to excommunicate. So if that isn’t the reason, what is?
For the good of sinners.
Scripture is quite clear on this. When St. Paul writes the Church in Corinth, he’s aghast that they are letting a man openly engage in a sexual relationship with his other stepmom. In fact, they had become proud of what they apparently thought of as their tolerance and mercy.
St. Paul rebukes them for this, writing:
“It is actually reported that there is immorality among you, and of a kind that is not found even among pagans; for a man is living with his father’s wife. And you are arrogant! Ought you not rather to mourn? Let him who has done this be removed from among you.
“For though absent in body I am present in spirit, and as if present, I have already pronounced judgment in the name of the Lord Jesus on the man who has done such a thing. When you are assembled, and my spirit is present, with the power of our Lord Jesus, you are to deliver this man to Satan for the destruction of the flesh, that his spirit may be saved in the day of the Lord Jesus.” (1 Corinthians 5.1-5)
He goes on to issue a general call for excommunication:
“I wrote to you in my letter not to associate with immoral men; not at all meaning the immoral of this world, or the greedy and robbers, or idolaters, since then you would need to go out of the world. But rather I wrote to you not to associate with any one who bears the name of brother if he is guilty of immorality or greed, or is an idolater, reviler, drunkard, or robber—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. ‘Drive out the wicked person from among you.'” (1 Corinthians 5.9-13)
So St. Paul clearly doesn’t fall into the “don’t excommunicate” camp, and he’s not impressed with the false tolerance of those who do.
But notice why he calls for the man’s excommunication. He orders him to be delivered to Satan “that his spirit may be saved in the day of the Lord Jesus.” In other words, you publicly condemn the man for the same reason you would tell a student that he’s failing: not to write him off, but to let him know that he needs to get his act together while there’s still time. Better to be condemned now and repent, than to be indulged in your sins now and condemned at the Last Judgment.
And note well, St. Paul’s tough love worked. Or at least, so it seems from his follow-up letter to the Corinthians:
“If anyone has caused grief, he has not so much grieved me as he has grieved all of you to some extent—not to put it too severely. The punishment inflicted on him by the majority is sufficient. Now instead, you ought to forgive and comfort him, so that he will not be overwhelmed by excessive sorrow. I urge you, therefore, to reaffirm your love for him.
“Another reason I wrote you was to see if you would stand the test and be obedient in everything. Anyone you forgive, I also forgive. And what I have forgiven—if there was anything to forgive—I have forgiven in the sight of Christ for your sake, in order that Satan might not outwit us. For we are not unaware of his schemes.” (2 Corinthians 2.5-11)
There’s a time to shame the sinning man, and there’s a time to comfort him so he isn’t overwhelmed by his shame and sorrow.
In other words, the excommunication was medicinal, it was for his good. Rather than looking on the sinning man as an enemy of the Church, Paul looked on him as an erring brother who needed to be rebuked to be brought back in line.
And Paul lays this model of Church discipline out succinctly in 2 Thessalonians 3.6, 14-15:
“Now we command you, brethren, in the name of our Lord Jesus Christ, that you keep away from any brother who is living in idleness and not in accord with the tradition that you received from us. […] If any one refuses to obey what we say in this letter, note that man, and have nothing to do with him, that he may be ashamed. Do not look on him as an enemy, but warn him as a brother.”
That’s a perfectly clear endorsement of the third of the three ways that I laid out above: excommunicate, but out of love, not an attempt to create a perfectly-pure Church.
So there it is: the basic case for why we should (and why we shouldn’t) excommunication.