"There is nothing, next to Christ and heaven, which Satan begrudges believers more than their peace and mutual love.
Now if the Gospel will not allow us to pay our enemies back in their own coin, returning anger for anger, then certainly it forbids a brother to spit fire into the face of another brother. When such embers of contention begin to smoke among Christians, we can be sure Satan planted the spark; he is the one great kindle-coal of all strife.
Whenever there is a storm in the spirits of saints, and the winds of their emotions are high and loud, it is easy to see who has stirred up the tempest. The devil practices his black art on unmortified lusts, that enable him to raise easily many storms of division among believers. Paul and Barnabas, for instance, set out in a calm together, but Satan sent a storm to part them in the middle of their journeyings: "And the contention was so sharp between them, that they departed asunder one from the other" (Acts 15:39).
There is nothing, next to Christ and heaven, which Satan begrudges believers more than their peace and mutual love. If he cannot separate them from Christ, and stop them from getting to heaven, he takes sinister pleasure in watching them get there in a storm. He would have them be like a shattered fleet separated from one another, saints deprived of the comfort and help of other Christians along the way. And when the devil can divide, he hopes to ruin also, knowing well that one ship is more easily taken than a squadron.
Now I love clear, calm air; but most of all I enjoy it in the church. I confess I am more aware of the greatness of this mercy when I see the dismal results of divisions that have troubled believers during these last years. What can I compare error to, better than smoke? And contention, than to fire? It is an emblem of hell itself, where darkness and flames meet to intensify the horror. But let me give you three reasons why a believer should give himself to peace and unity.”.”Quoted material from, ”The Christian in Complete Armour Daily Readings in Spiritual Warfare” by Gurnall and James S Bell. http://www.moodypublishers.com/pub_productDetail.aspx?id=41823&pid=53617