"but speaking the truth in love, we are to grow up in all aspects into Him who is the Head, even Christ."
Paul touches on three immeasurably important needs for every believer: (1) what we're to speak, (2) how we're to speak, and (3) the goal of a well-rounded maturity in the Lord Jesus.
(1) As those whose souls have been savingly changed by the regenerating work of the Holy Spirit, our lives are to be continually transformed by the renewing of our minds. Our minds (hearts) are the focus here, because our mouths speak that which fills our hearts (Luke 6:45). And it's important what we say, even every word we speak -- "And I say to you, that every careless word that men shall speak, they shall render account for it in the day of judgment. For by your words you shall be justified, and by your words you shall be condemned." (Matthew 12:36, 37). Sobering words, these... especially since the Lord Jesus never exaggerated, never equivocated, never misspoke. As our speech is a reflection of our heart's condition, what we say actually forms a basis for future judgment: believers before the bema seat of Christ (II Corinthians 5:10), and the unsaved before the Great White Throne (Revelation 20:11-13). What then are we to speak? The truth. Sounds simple, but it isn't. We can lie in so many more ways that stating a falsehood. One of the most subtle ones is silence. By our silence we can allow others to assume an untruth. And with our pride and fears and deceitful hearts (Jeremiah 17:9), silence isn't "golden", it's sinful. Another pitfall comes in the form of exaggeration. Overstating to impress easily slips into falsities that multiply and worsen, until we are inextricably caught in them, and our good name (as well as our witness) are compromised. One other way we may mishandle the truth is to speak it as a weapon, with the intent to hurt. Incalculable damage has been done to the body of Christ, even to the destroying of fellowships, by some who declare, with cruelty, truth that tears down rather than builds up... which leads to the "how we are to speak."
(2) Speaking the truth can be harsh, biting, and hurtful... particularly if it's told to the wrong person, behind another's back, with ulterior motives. Gossip can be malicious, even though the information may be true. And some seek to justify overly-confrontational truth by pleading the spiritual gift of prophecy. Hence, Paul bids us balance truth-telling with love. The biblical portrayal of love is not a sugary sentimentality, based on feelings. Paul's enduring all that he did (II Corinthians 11:23-27), was certainly not based on emotion or mood. And the supreme example of love's sacrificial nature, despite feelings, is the crucifixion of the Lord Jesus... He definitely did not feel like being nailed to a cross... yet sacrificial love and submission to His Father kept Him there. The point? Speaking the truth doesn't always feel good, yet when spoken in loving obedience to the Lord and for the listener's sake, the Holy Spirit's smile will be upon it. There is not a guarantee that the truth will be received gladly... yet the Lord will be pleased, and we will grow from it.
(3) Spiritual maturity, leading to being conformed more and more to the image of Christ, is Paul's goal for the Ephesian believers in this verse... and by extension, all who have been changed by the Lord Jesus. James' perspective agrees with Paul's: "For we all stumble in many ways. If anyone does not stumble in what he says, he is a perfect man, able to bridle the whole body as well," (3:2). "Perfect" could be taken literally, but more likely it indicates maturity...the spiritual maturity of those who have learned to minimize their tongues' misuse. I say minimize rather than "completely control" because of James' statement in verse 8 of that third chapter: "But no one can tame the tongue; it is a restless evil and full of deadly poison." Thus, a sign of spiritual maturity is constant vigilance and yieldedness to the Holy Spirit's ministry, thereby taking captive to His obedience our every thought. For, when our thoughts are pure, then our speech will be, as well. O that we would keep our focus upon the Lord Jesus, Author and Finisher of our faith, that by His Word both our contemplations and conversations would have His empowering grace.