The topic of unity is often cited as a Christian virtue, something to be maintained on its own merits. We tend to look at unity as a virtue, like love, righteousness and the like. However, unity is not a virtue. It is a two-edged sword that brings the potential for great benefits as well as the potential for great harm.
One frequently- cited passage discussing the benefits of unity is Genesis 11:
Now the whole earth used the same language and the same words.  And it came about as they journeyed east, that they found a plain in the land of Shinar and settled there.  And they said to one another, "Come, let us make bricks and burn them thoroughly." And they used brick for stone, and they used tar for mortar.  And they said, "Come, let us build for ourselves a city, and a tower whose top will reach into heaven, and let us make for ourselves a name; lest we be scattered abroad over the face of the whole earth."  And the LORD came down to see the city and the tower which the sons of men had built.  And the LORD said, "Behold, they are one people, and they all have the same language. And this is what they began to do, and now nothing which they purpose to do will be impossible for them.  "Come, let Us go down and there confuse their language, that they may not understand one another's speech."  So the LORD scattered them abroad from there over the face of the whole earth; and they stopped building the city.  Therefore its name was called Babel, because there the LORD confused the language of the whole earth; and from there the LORD scattered them abroad over the face of the whole earth. (Genesis 11:1-9)
Usually when unity is preached on and this passage is used, the message is "look how much people can do when they just work together." And that is true-- a well organized group of people can accomplish far more than any number of individuals working on their own. This is one of the great things about unity.
But something rarely observed about this passage is that these people were united in sin. Their collective sinful nature and desire for self worship ("let us make a name for ourselves"), when coupled with unity, made for a situation that was so evil that God himself had to address with an unprecedented pair of actions-- confusing their language and scattering them.
The people of Shinar were able to do a far greater wrong collectively than any of the them could have done individually. This reminds me of the old saying in the information technology business: "To err is human, to really foul things up requires a computer." But given our human propensity for sin, we might modify this saying just a bit: "To err is human, to really foul things up requires a group."
Clearly, unity is morally neutral; it can be used for either good or evil.
The Pharisee's in Jesus' day had an interesting unity. Consider the following passages from the gospel of John:
The officers therefore came to the chief priests and Pharisees, and they said to them, "Why did you not bring Him?"  The officers answered, "Never did a man speak the way this man speaks."  The Pharisees therefore answered them, "You have not also been led astray, have you?  "No one of the rulers or Pharisees has believed in Him, has he?  "But this multitude which does not know the Law is accursed."  Nicodemus said to them (he who came to Him before, being one of them),  "Our Law does not judge a man, unless it first hears from him and knows what he is doing, does it?"  They answered and said to him, "You are not also from Galilee, are you? Search, and see that no prophet arises out of Galilee." (John 7:45-52)
Nevertheless many even of the rulers believed in Him, but because of the Pharisees they were not confessing Him, lest they should be put out of the synagogue;  for they loved the approval of men rather than the approval of God. (John 12:42-43)
Their unity squelched questioning, individual convictions and faith in favor of maintaining loyalty and solidarity within the group. They were "united," but it was contrived. This unity was little more than a control mechanism. Those who dared challenge the leaders of the group were dealt with harshly and driven out. The group's leaders would stop at nothing to protect their positions of control over the group:
Therefore the chief priests and the Pharisees convened a council, and were saying, "What are we doing? For this man is performing many signs.  "If we let Him go on like this, all men will believe in Him, and the Romans will come and take away both our place and our nation."  But a certain one of them, Caiaphas, who was high priest that year, said to them, "You know nothing at all,  nor do you take into account that it is expedient for you that one man should die for the people, and that the whole nation should not perish."  Now this he did not say on his own initiative; but being high priest that year, he prophesied that Jesus was going to die for the nation,  and not for the nation only, but that He might also gather together into one the children of God who are scattered abroad.  So from that day on they planned together to kill Him. (John 11:47-53)
Jesus challenged the heart of this warped sense of unity:
How can you believe, when you receive glory from one another, and you do not seek the glory that is from the one and only God? (John 5:44)
In this example of the Pharisees, we can see that maintaining their group identity was fundamentally about seeking the approval of people over the approval of God. Not only is such a unity deceptive, it is diametrically opposed to true faith in Jesus.
In his book "People of the Lie," Dr. M. Scott Peck goes into a lengthy discussion on the topic of unhealthy dynamics in groups.
First, Peck identifies the characteristics of regression of individuals in a group. Simply, people in groups tend to regress and be less mature, and less mature people are more inclined to do wrong.
For many years it has seemed to me that human groups tend to behave in much the same ways as human individuals-- except at a level that is more primitive and immature than one might expect. Why this is so-- why the behavior of groups is strikingly immature--why they are, from a psychological standpoint, less than the sum of their parts-- is a question beyond my capacity to answer. Of one thing I am certain, however: that there is more than one right answer. The phenomenon of group immaturity is-- to use a psychiatric term-- "overdetermined." This is to say that it is the result of multiple causes. (Peck, People of the Lie, p. 214)
Second, Peck mentions the phenomenon of specialization within a group-- people having different roles where they are somewhat isolated from the "big picture." While this has potential to help a group accomplish good, it has many important aspects that make it easier for a group to do something bad.
Peck suggests that people in any group tend to rely upon leaders in that group not out of humility but out of laziness. The delineation between leaders and non-leaders is the first instance of specialization within a group. It gives the leaders a degree of control over group members.
The phenomenon of leadership and authority in the chain of doing something wrong is fascinating. Peck cites the research studies by Stanley Milgram who found that a majority of subjects (of various cultural and educational groups) were willing to inflict pain upon people simply because someone in authority told them to do it and was willing to "take responsibility" for it. This shows that humans under authority will follow that authority even if it hurts others, as their conscience easily assigns responsibility for their actions to the authority.
Whenever the roles of individuals within a group become specialized, it becomes both possible and easy for the individual to pass the moral buck to some other part of the group. In this way, not only does the individual forsake his conscience but the conscience of the group as a whole can become so fragmented and diluted as to be nonexistent. (Peck, ibid, p. 218)
Simply, groups do not have a conscience like individuals. At best, specialization permits everybody in the group to assume that "somebody else" is watching out for the impact of the group. Of course, if everybody thinks that, then nobody is watching and "the blind are leading the blind."
Thirdly, Peck identifies lack of self-examination, low tolerance of self-criticism and the group identity as powerful forces in group dynamics. Groups naturally invent enemies if they don't have one already. They will naturally reinforce the goodness of the group compared to the evil of the enemy. Caught up in the question of its justification for existence, a group can be unwilling to consider that it might be flawed or misguided in any way.
Some might question the legitimacy of these observations about group dynamics because they "aren't in the Bible." However, when we consider instances of group wrongdoing in the Bible these traits are clearly evident-- for example, the crucifixion of Jesus, the harassment of the healed blind man (John 9), the Ephesian riot (Acts 19) and others. Thus, this expression of these traits should not be rejected.
When one puts these concepts together, the potential for wrongdoing in a group is real and intrinsically greater than the potential for good. This point should be sobering to all members of a church.
Properly sobered by a consideration of the potential for group wrongdoing, we need to learn to discern between a Scriptural definition of unity and a worldly definition of unity. As we have seen at Babel or the Pharisees' council chambers, unity can be a power factor in wrongdoing. By contrast it should also be intuitively obvious that God's prescription of unity for the church will not easily facilitate the doing of wrong. Neither should it be the result of carnal shortcomings such as laziness or immaturity. It cannot be an instrument that inhibits individual faith or harms the individual conscience. Any such "unity" is worldly and a ready tool for potential wrongdoing.
From the pages of the New Testament, unity is always a secondary characteristic that follows from people being faithful to Jesus. Consider the following familiar passage:
My prayer is not for them alone. I pray also for those who will believe in me through their message,  that all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me.  I have given them the glory that you gave me, that they may be one as we are one:  I in them and you in me. May they be brought to complete unity to let the world know that you sent me and have loved them even as you have loved me. (John 17:20-23)
Unity is built upon the faithfulness of individuals.
In his letters to the Corinthians, Paul dealt with the topic of divisions and church conflicts repeatedly. Interestingly, he observed that divisions were actually necessary in a church. The very existence of divisions in the Corinthian congregation shows that unity was a goal in the church and not a foundational element of the faith. Echoing the sentiments of John 17, Paul indicated that unity was the result of individuals living faithfully and, to a certain extent, the work of God within the individual congregation:
Now I exhort you, brethren, by the name of our Lord Jesus Christ, that you all agree, and there be no divisions among you, but you be made complete in the same mind and in the same judgment.  For I have been informed concerning you, my brethren, by Chloe's people, that there are quarrels among you. (1 Corinthians 1:10-11)
For, in the first place, when you come together as a church, I hear that divisions exist among you; and in part, I believe it.  For there must also be factions among you, in order that those who are approved may have become evident among you. (1 Corinthians 11:18-19)
Even to the churches in Asia Minor that received John's Revelation, those who "bucked the trend" towards sin in their congregations were praised for their righteousness, not chastised for being disunited from the rest of the church:
But I say to you, the rest who are in Thyatira, who do not hold this teaching, who have not known the deep things of Satan, as they call them--I place no other burden on you. (Revelation 2:24)
But you have a few people in Sardis who have not soiled their garments; and they will walk with Me in white; for they are worthy. (Revelation 3:4)
Sometimes division is necessary when the congregation as a whole is failing in certain areas. Those seeking the approval of God in such circumstances need not feel torn between unity and faithfulness; faithfulness is clearly the most important element.
I, therefore, the prisoner of the Lord, entreat you to walk in a manner worthy of the calling with which you have been called,  with all humility and gentleness, with patience, showing forbearance to one another in love,  being diligent to preserve the unity of the Spirit in the bond of peace. (Ephesians 4:1-3)
And He gave some as apostles, and some as prophets, and some as evangelists, and some as pastors and teachers,  for the equipping of the saints for the work of service, to the building up of the body of Christ;  until we all attain to the unity of the faith, and of the knowledge of the Son of God, to a mature man, to the measure of the stature which belongs to the fulness of Christ. (Ephesians 4:11-13)
If therefore there is any encouragement in Christ, if there is any consolation of love, if there is any fellowship of the Spirit, if any affection and compassion,  make my joy complete by being of the same mind, maintaining the same love, united in spirit, intent on one purpose.  Do nothing from selfishness or empty conceit, but with humility of mind let each of you regard one another as more important than himself;  do not merely look out for your own personal interests, but also for the interests of others. (Philippians 2:1-4)
Now may the God who gives perseverance and encouragement grant you to be of the same mind with one another according to Christ Jesus;  that with one accord you may with one voice glorify the God and Father of our Lord Jesus Christ. (Romans 15:5-6)
Paul also recognized that a wide variety of issues exist that can potentially divide the church in a hurtful way. He strongly urged that these be dealt with in ways that would both maintain unity and preserve the integrity and consciences of individuals that might believe differently than others.
Therefore let us not judge one another anymore, but rather determine this--not to put an obstacle or a stumbling block in a brother's way... The faith which you have, have as your own conviction before God. (Romans 14:13, 22).
For through your knowledge he who is weak is ruined, the brother for whose sake Christ died.  And thus, by sinning against the brethren and wounding their conscience when it is weak, you sin against Christ. (1 Corinthians 8:11-12)
In these discussions, Paul made the argument that there were "right" and "wrong" positions on many of the issues at hand. Yet because of the relative insignificance of these matters compared to the gospel, he would not allow these matters to become a source of offense or division to individuals in the church. A unity that runs roughshod over individuals for the good of the group or for others in the group is spoken against by the Scriptures.
The Scriptures teach that the church is like a body having many parts with different functions. This concept holds up the idea of individuality (compared to conformity) and care within the body for the benefit of the various members of the body.
And the eye cannot say to the hand, "I have no need of you"; or again the head to the feet, "I have no need of you."  On the contrary, it is much truer that the members of the body which seem to be weaker are necessary;  and those members of the body, which we deem less honorable, on these we bestow more abundant honor, and our unseemly members come to have more abundant seemliness,  whereas our seemly members have no need of it. But God has so composed the body, giving more abundant honor to that member which lacked,  that there should be no division in the body, but that the members should have the same care for one another.  And if one member suffers, all the members suffer with it; if one member is honored, all the members rejoice with it. (1 Corinthians 12:21-26)
For just as we have many members in one body and all the members do not have the same function,  so we, who are many, are one body in Christ, and individually members one of another.  And since we have gifts that differ according to the grace given to us, let each exercise them accordingly: if prophecy, according to the proportion of his faith;  if service, in his serving; or he who teaches, in his teaching;  or he who exhorts, in his exhortation; he who gives, with liberality; he who leads, with diligence; he who shows mercy, with cheerfulness. Let love be without hypocrisy. Abhor what is evil; cling to what is good.  Be devoted to one another in brotherly love; give preference to one another in honor; (Romans 12:4-10)
As each one has received a special gift, employ it in serving one another, as good stewards of the manifold grace of God.  Whoever speaks, let him speak, as it were, the utterances of God; whoever serves, let him do so as by the strength which God supplies; so that in all things God may be glorified through Jesus Christ, to whom belongs the glory and dominion forever and ever. Amen. (1 Peter 4:10-11)
Specialization is a part of life, reflecting God-created human diversity. It isn't inherently evil; indeed it can serve many benefits when governed by love and respect for God. But when it is accompanied by the unhealthy characteristics mentioned elsewhere in this article, it could be a tool for wrongdoing.
Let's summarize the "do's and don'ts" dynamics associated with groups:
Christians have to "fight nature" in regards to unity by paying special attention to these dos and don'ts. Scriptural unity is radically different from standard group unity, and natural group dynamics can be destructive to the faith of individuals.
To those concerned about a more healthy and Biblical unity:
No doubt many more traits of healthy and unhealthy group dynamics could be discussed. I hope this discussion stimulates further consideration and study on this topic.
I have no doubt that unity is morally neutral, and that unhealthy unity in a church can have some terrible consequences. We ought to concern ourselves more with faithfulness (seeking God's will and approval) than simply maintaining "unity" as though it is the virtue that negates all shortcomings. Love may cover over a multitude of sins, but unity does not.
False unity can be declared or enforced via external means by the foolish or impatient, but true unity will come in time to those who are personally dedicated to being faithful to Jesus. Having seen true unity before, and having seen the alternative, I think true unity is worth the wait.