Paul’s letter to the Ephesians is typical of his correspondence to other churches in that the first half of the letter is devoted to outlining the various doctrines that are constituent parts of the gospel message. Throughout his letters, the apostle has a great deal to say about Christian conduct, but it is always done in light of the mercies received and the grace given.
For example, the first three chapters of Ephesians focus almost entirely on the riches of God’s grace as it is found in the person and work of Christ. In the second half of the letter, Paul, using those present realities as his backdrop, exhorts the Ephesians with a number of imperatives. He begins the exhortations in chapter 4: “I therefore, a prisoner for the Lord, urge you to walk worthy of the calling to which you have been called.” In verses 17—24, Paul is even more explicit in applying the grace received to the manner in which Christians are to live their lives: “You must no longer walk as the Gentiles do, in the futility of their minds” (v. 17). His rationale in verse 18 is that the other (unregenerate) Gentiles are “darkened in their understanding, alienated from the life of God.” He goes on to say that this is “due to their hardness of heart.”
In verses 20–22, Paul contrasts the Ephesians with other Gentiles by reminding them of what they have been taught in and by Christ. The conduct that he admonishes in verses 25–32 (and throughout the remainder of the letter) is not only in light of the grace they have received in the gospel but also in light of their condition before conversion and what they are presently being taught. To be more accurate, one of the things they had received in the gospel is a new heart awakened to the righteousness of God’s law and enabled by His Spirit to pursue it. The gift of a renewed heart is part of what is promised in the new covenant (see Jer. 31:33). Ezekiel 36:26–27 is explicit: “And I will give you a new heart, and a new spirit I will put within you. And I will remove the heart of stone from your flesh and give you a heart of flesh. And I will put my Spirit within you, and cause you to walk in my statutes and be careful to obey my rules.”
One might argue that even the apostle Paul acknowledges that Gentiles have the law written on their hearts (Rom. 2:15). Yes, all men and women have some sense of a moral standard, but the unregenerate do not have God as the basis of their moral standard. Paul’s point in Romans 1:19– 23 is that even if the morality of the unregenerate is religiously motivated, their darkened hearts cause their conception of God and their sense of connection to Him to be distorted.
The metaphor of a “heart of stone” used in Ezekiel 36 and the “hardness of heart” alluded to in Ephesians 4:18 are apt descriptions of the unregenerate condition because they punctuate the inability of the human heart to respond to God and to the things of God — particularly His law. This is what Paul refers to as “dead in the trespasses and sins in which you once walked” in Ephesians 2:1–2. But as promised in Ezekiel, God has “removed the heart of stone” and replaced it with a “heart of flesh.”
This removal and replacement is the regenerating work of the Holy Spirit, which animates the soul with new and holy affections, appetites, and abilities. In Philippians 2:13, Paul says, “It is God who works in you, both to will and to work for his good pleasure.” The exhortations that are set forth in Ephesians 4:25–32 are to those who are recipients of the grace outlined in the first three chapters.
The gospel announces what God graciously gives in the person and work of His Son, which includes the imputation of His righteousness for our justification. God’s promises also include the gifts of a new heart and new affections toward His law, from which our sanctification flows. The conclusion Paul makes is that the beauty and majesty of the law of God that was obscured and distorted by sin has now (by the regenerating light of His Spirit) been renewed in the hearts of His chosen people. Therefore, as the sanctifying work of the Spirit conforms each of God’s children to the image of His Son, our behavior (words, thoughts, and deeds) will be motivated by proper love for God our Father and proper love for our neighbors.
Two things should be noted here. First, Christian morality is never a matter of keeping God’s law as a means of gaining a right standing with Him. Second, Christian morality is not mere conformity to abstract rules of conduct. As Walther Eichrodt has observed in his Theology of the Old Testament: “Inasmuch as the will of God emerges as the supreme norm behind all particular requirements, the desired unity of the moral sphere shifts in essence to the personal activity of the covenant God.” God’s commandments are an eternal reality for His covenant people because He has written His law on our hearts and has awakened us to His holy will. Our sanctification consists in a growing disaffection for the will of the flesh (our fallen nature) and a growing affection for the will of God.