These things I command you, that ye love one another. John 15:17.
Christ’s prayer [in John 17] ... is an illustration of the intercession that He is offering for us before the Father.
“Sanctify them through thy truth: thy word is truth,” He prayed (Verse 17). “As thou hast sent me into the world, even so have I also sent them into the world. And for their sakes I sanctify myself, that they also might be sanctified through the truth.
“Neither pray I for these alone, but for them also which shall believe on me through their word; that they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me. And the glory which thou gavest me I have given them; that they may be one, even as we are one: I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me” (Verses 18-23).
Today the One who uttered this prayer is interceding before the Father in behalf of the human beings He has redeemed. He presents them to Jehovah, saying, “I have graven them upon the palms of My hands” (cf. Isaiah 49:16).
Sanctification is to come through the truth; oneness with Christ— this is God’s purpose for us. By their sanctification and their unity, Christians are to give evidence to the world that a perfect work has been done for them, in and through Christ. Thus they are to bear witness that God sent His Son to save sinners. Will you not let Christ carry on this work of sanctification in your hearts? You may all be complete in Him. You have the assurance that through the sanctification of the truth you may be made perfect in one...
The Savior is acquainted with the mental suffering of His children. He knows how at times their hearts are wounded and bleeding. He would have the afflicted soothed and helped. He says to us, “Bear ye one another’s burdens” (Galatians 6:2). “We then that are strong ought to bear the infirmities of the weak, and not to please ourselves” (Romans 15:1). We are to relate ourselves rightly to one another, even though to do this demands sacrifice. Christ made an infinite sacrifice for us, and should we not be willing to sacrifice for others? We are to guard carefully against wounding or bruising the hearts of God’s children, for when we do this, we wound and bruise the heart of Christ.—Letter 31, January 17, 1904, to Elder and Mrs. J. A. Burden, and Dr. and Mrs. D. H. Kress.
Reference: E.G. White, "The Upward Look," p. 31