In the closing of his epistle to the Romans, Paul writes, "I appeal to you, brothers, to watch out for those who cause divisions and create obstacles contrary to the doctrine that you have been taught; avoid them" (Romans 16:17). Paul is not appealing that Christians avoid any division, but those divisions contrary to the truth of the Scripture. Paul is appealing for Christians to unite in the truth of Scripture and to separate from those challenging the Word of Truth.
Unity in Truth is True Unity
This is not the post-modern message in the West, which defines unity as avoiding any and all division in tolerance of all beliefs and doctrines as equally valid and acceptable. For the apostle Paul, unity is found only in "the doctrine that you have been taught." Christ perfects, equips, and gifts His people through the Word "divided accurately" (II Timothy 2:15) until "we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ, so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes" (Ephesians 4:13-14). Paul contends that the saints are not brought to "the fullness of Christ" and perfected by smart preachers or human wisdom, but by Christ Himself through His perfect Word.
In Colossians 3, Paul commands the local church to have hearts ruled by the peace of Christ and put on love, "which is the perfect bond of peace" (Colossians 3:14-15). Our understanding of true unity and peace and love of Christ are not to simply take verses out of context and redefine the meaning. Paul finishes in verse 16 with, "Let the Word of Christ richly dwell within you, with all teaching and admonishing one another..." Our peace and love of Christ is ruled ultimately by Scripture, which so abundantly takes up residence in our hearts that we teach and admonish one another. Christ washes His local church with His Word (Ephesians 5:26), and Paul commends the God-breathed Scripture for "teaching, for reproof, for correction, and for training in righteousness," which equips us for every good work (II Timothy 3:16-17).
Unity in the truth of Scripture is the only true unity Christ graces for His church. Unity in the truth means not to have a problem with authority of Christ in His perfect Word, but to have problems with authority from any other source, including a self-distrust.
The Singularity of Truth
Paul consistently speaks of the truth (singular, not plural) of Scripture. Paul states that unashamed believers can "rightly divide the Word of Truth," claiming Scripture to be one, cohesive, consistent, non-contradictory revelation of truth. Paul supposes that, although difficult to understand at times, the Scripture is clear and speaks of truth, giving full authority to the Word's Author and no authority to the reader. In other words, the reader is not permitted to suggest truth into Scripture that is not there, but the Author reveals truth to the reader that did not know. For instance, Paul commands the local church in Ephesus to "Speak the truth in love." Not truth(s), or kindly suggest an opinion and happily agree that everyone has their own opinion or "personal interpretation", or be kind and "lovingly" never confront anyone with the truth of Scripture, but speak the TRUTH.
The singularity of truth in Scripture contends that God is sovereign; in other words, God is in full control and fully capable of revealing truth to us in a clear manner. Our reading of Scripture must be of an attitude of complete dependence and trust in God to reveal truth to us, lest we claim partial or complete sovereignty of truth. Remember, Scripture tells us that without Christ we are blinded by Satan (II Corinthians 4:4), not dimly seeing. Without Christ we are dead in our trespasses and sins (Ephesians 2:1), not merely sick or wounded. To challenge truth with our opinions or to suggest parts that we do not like are antiquated or contradictory challenges God's sovereign authority in His Word, which causes divisions and sets up obstacles in the church.
Paul goes so far as to command the local church in Rome to avoid those who cause divisions and create obstacles contrary to the truth of Scripture. Avoid them. Paul suggests that in order to serve Christ and not be a people-pleaser, we are to be united in the gospel (again, singular) and reveals that if anyone including angels preaches another gospel contrary to Scripture, that person is eternally accursed (Galatians 1:6-10). Paul handed false teachers "over to Satan" for spinning a different teaching of the gospel.
To remove people from congregation in church discipline or to correct others with the Scripture seems intolerant or divisive in this day and age. However, biblically speaking, we are to unite in the truth of Scripture alone, and avoid and separate ourselves from those teaching otherwise. Some might suggest that Christians can unite with others to get work done. However, to compromise truth for pragmatism sets the church up for human cunning and deceitful schemes, placing what we do above the truth.
However, Paul does command the local church to be "eager to maintain the unity of the Spirit in the bond of peace" (Ephesians 4:3). We must yearn for unity, but unity is something the local church maintains (guard, keep) not creates. Unity in the truth of the Word of God is given to us by Christ, not made up by groups of people in our own opinions and suggestions while leaning on our own understanding. We must be eager, with gut-gripping yearning for the saints to be unified in peace bound by Christ's love and provided by His Word of Truth.