Beloved, if God so loved us, we ought also to love one another. 1 John 4:11.
The world is looking with gratification at the disunion [seen] among Christians. Infidelity is well pleased. God calls for a change among His people. Union with Christ and with one another is our only safety in these last days. Let us not make it possible for Satan to point to our church members, saying, “Behold how these people, standing under the banner of Christ, hate one another. We have nothing to fear from them while they spend more strength fighting one another than in warfare with my forces.”
After the descent of the Holy Spirit, the disciples went forth to proclaim a risen Saviour, their one desire the salvation of souls. They rejoiced in the sweetness of communion with saints. They were tender, thoughtful, self-denying, willing to make any sacrifice for the truth’s sake. In their daily association with one another they revealed the love that Christ had commanded them to reveal. By unselfish words and deeds they strove to kindle this love in other hearts...
But the early Christians began to look for defects in one another. Dwelling upon mistakes, encouraging suspicion and doubt, giving way to unkind criticism, they lost sight of the Saviour and of the great love He had revealed for sinners. They became more strict in regard to outward ceremonies, more particular about the theory of the faith, more severe in their criticisms. In their zeal to condemn others, they themselves erred. They forgot the lesson of brotherly love that Christ had taught. And, saddest of all, they were unconscious of their loss. They did not realize that happiness and joy were going out of their lives, and that soon they would walk in darkness, having shut the love of God out of their hearts.
The apostle John realized that brotherly love was waning in the church, and he dwelt particularly upon this point. Up to the day of his death, he urged upon believers the constant exercise of love for one another...
In the church of God today brotherly love is greatly lacking. Many of those who profess to love the Saviour neglect to love those who are united with them in Christian fellowship...
Harmony and unity existing among men of varied dispositions is the strongest witness that can be borne that God has sent His Son into the world to save sinners. It is our privilege to bear this witness. But in order to do this, we must place ourselves under Christ’s command. Our characters must be molded in harmony with Christ’s character; our wills must be surrendered to His will.—Manuscript 143, December 10, 1903, “Unity.”
Reference: E.G. White, "The Upward Look," p. 358.