“But speaking the truth in love, may grow up into him in all things, which is the head even Christ” (Eph 4:15)
The Twentieth Century New Testament translates this verse as follows: “but holding the truth in a spirit of love, we shall grow into complete union with him who is our Head–Christ himself”
Barnes’ Notes on the Bible
But speaking the truth in love – Margin, “being sincere.” The translation in the text is correct – literally, “truthing in love” – ἀληθεύοντες alētheuontes. Two things are here to be noted:
(1) The truth is “to be spoken” – the simple, unvarnished truth. This is the way to avoid error, and this is the way to preserve others from error. In opposition to all trick, and art, and cunning, and fraud, and deception, Christians are to speak the simple truth, and nothing but the truth. Every statement which they make should be unvarnished truth; every promise which they make should be true; every representation which they make of the sentiments of others should be simple truth. “Truth is the representation of things as they are;” and there is no virtue that is more valuable in a Christian than the love of simple truth.
(2) the second thing is, that the truth should be spoken “in love.” There are other ways of speaking truth. It is sometimes spoken in a harsh, crabby, sour manner, which does nothing but disgust and offend. When we state truth to others, it should be with love to their souls, and with a sincere desire to do them good. When we admonish a brother of his faults, it should not be in a harsh and unfeeling manner, but in love. It should not be done in a harsh and repulsive manner;….. it should not be with indifference, or in a tone of superiority…..if we go to convince one who is in error, we should approach him in love. Such things only repel. “He has done about half his work in convincing another of error who has first convinced him that he loves him;” and if he does not do that, he may argue to the hour of his death and make no progress in convincing him.