An interesting study can be found on the following link: http://www.gotquestions.org/church-unity.html. The original article is in the link that is mentioned in the first sentence.
For ease of reference and reading, I have copy pasted the article below from the GOTQUESTIONS.ORG website.
How can the church achieve a true, biblical unity?
Answer: The Bible underscores the importance of “unity” and “oneness.” Unity with others is “good” and “pleasant” (Psalm 133:1). Unity is absolutely essential because the church is the “body of Christ” (1 Corinthians 12:27), and a body cannot be in disunity or disharmony with itself. If disunity occurs, it essentially ceases to be a body and becomes a disjointed group of individuals. Jesus’ plan for His church is people unified in the faith.
The secret to unity begins with how we view ourselves within the body and how we view others. The key verse that addresses this is Philippians 2:3: “Do nothing out of selfish ambition or vain conceit, but in humility consider others better than yourselves.” All disunity in a church can be traced back to the simple truth that too often we act selfishly and consider ourselves better than others. Paul goes on to explain further in the following verse: “Each of you should look not only to your own interests, but also to the interests of others.” Sadly, churches that experience disunity and are in conflict and turmoil are generally filled with people looking to their own needs, their own desires, and their own ambitions. Such behavior is characteristic of unbelievers, not those with the mind of Christ. Worldliness, not godliness, is the hallmark of the disunified church, as Paul reminded the Corinthians: “For you are yet carnal. For in that there is among you envyings and strife and divisions, are you not carnal, and do you not walk according to men?” (1 Corinthians 3:3).
But Paul tells us that we are to consider others’ needs before our own. In all modesty, humility and lowliness of mind, we are to “be completely humble and gentle; be patient, bearing with one another in love” (Ephesians 4:2). A church filled with such people cannot help but have peace, unity and harmony. The truly humble person sees his own faults in light of the perfections of Christ; he does not seek to see the faults of others, but when he does, he speaks the truth in love and desires their sanctification so they will be built up in the image of Christ. He sees his own heart and the corruption that lies hidden there, along with impure motives and evil ambitions. But he does not seek to notice the errors, defects, and follies of others. He sees the depravity of his own heart and hopes charitably in the goodness of others and believes their hearts are more pure than his.
Most importantly, as Christians, we are to see one another in the light of the cross. Fellow Christians are those for whom Christ died a horrible and painful death so that He might exchange His righteous perfection for their sin (2 Corinthians 5:21). How can we not extend to them the love, compassion, and grace of our heavenly Father?How can we demean, criticize, and defame those covered with the precious blood of Christ? Were we not slaves to sin when He called us, hopelessly lost, dead in our own transgressions and sins (Ephesians 2:1)? But we are now slaves of Christ, slaves to righteousness, and as slaves of the Master, the task before us is not to quarrel and demand our needs be met but to reflect His grace and love to those who are also His by His mercy. A church full of such people enjoying their “common salvation” will be a true, biblical church unified in, and earnestly contending for, the “faith once delivered to the saints” (Jude 1:3).
Is there anything we as believers can now build on this?