In "God's Word for Today" David Woods writes:

There may be many reasons why local churches do not seek greater unity today. Some are paranoid that working together in the local church and with other like-minded churches in the area will result in everyone being deceived by a one-world false church. Others are so embittered against fellow Christians — in other nearby churches, or even within their local congregation — that they will not allow themselves or others to seek reconciliation and unity. Maybe an even greater difficulty is the inability of many to envision how unity might look in our post-modern context. How is it possible to achieve unity with churches around the world? How can we reconcile our doctrinal and traditional differences with other churches? The key to solving this dilemma may be to ask the question of how to experience greater unity locally instead of in a universal sense.

Source: Building Christian Relationships: Adult Teacher's Insights, page 19.