Ephesians 4:15 "Speaking the Truth in Love"

John Piper in a sermon on October 25, 1992 comments on the phrase in Ephesians 4:15: speaking the truth in love.

Let me clear up a wrong idea here that I had for years about this phrase because I ignored the context. I used to think that the phrase, "speak the truth in love," meant, "Tell it like it is, but gently." Like: if a student bombed a test or if a man loses his job, you may have to do the tough work of telling them the truth, but you do it in love to soften the blow. So the truth which is in view here, I thought, was just the hard facts of life that a person might need to hear about in love. Well, that is no doubt part of the meaning here (especially in view of Ephesians 4:25) but the context points in a different direction, that is very crucial to see for the good of the church. The context is all about doctrinal truth—truth about God and about his Son. Notice three evidences of this.
The Context is all about Doctrinal Truth

First, the equippers of the saints in verse 11 are all truth agents: apostles (the authoritative, foundational witnesses to the truth), the prophets (the charismatic speakers of truth that apply it with supernaturally guided pointedness), the evangelists (who do the work of evangelism with the truth of the gospel in regions where apostles have planted the church), the pastors and teachers (who take the truth and use it to feed and protect the flock of God). Every one of these offices centers on the truth of God and Christ and the gospel. These people are truth agents.

Second, verse 13 says that the goal of building up the body of Christ is to attain to the unity of the faith and the knowledge of the Son of God. So the building begins with equippers who are all agents of truth, and the aim of the building is unified knowledge, that is, unified grasp of truth.

Third, we have seen that verse 14 shows Paul's great concern is that as we grow into corporate Christlikeness, we are not to be babes who are blown around by every wind of doctrine. So again the issue is stability in true doctrine so that we will not be deceived by false doctrine.

O'Brien's commentary points out the same idea.

... the apostle is not exhorting his readers to truthfulness in general or speaking honestly with one another, however appropriate or important this may be. Rather, he wants all of them to be members of a 'confessing ' church, with the content of their testimony to be 'the word of truth', the gospel of their salvation (1:13). This truth, which is guaranteed by God and is depicted as part of his own armour, is the belt which believers are to buckle around their waist as they resist the onslaughts of the evil one (6:14).

As Christians witness to the truth of the gospel they cannot use the same methods as the false teachers or the tempter whose activity lies behind them. (O'Brien, The Letter to the Ephesians" p. 311)

I have posted this quote before from Mike Cosper about "speaking the truth in love."

Speaking the truth in love” is often understood as saying hard things or dealing with conflict: we “speak the truth in love” when we confront sin or say unpopular things lovingly. According to Peterson, though, “speaking the truth in love” is not so much about interpersonal boldness as it is about a community that shares a confession, a unified expression of faith in the God who saved them. The gathered body teaches the Word and proclaims it together; we speak the truth I love as we sing, read the Scriptures, and remember the gospel together. (Rhythms of Grace, Mike Cosper, p. 80).

Although exhortation is a key tool for building up the church, Paul is concentrating in Ephesians about doctrinal truth. We are to celebrate the truth of the gospel through our preaching, worship, and love. The path to maturity that Paul is describing is in steadfastness to the truth and love. It is not emotional maturity, although that is important, it is not what Paul is stressing in Ephesians.