This article address the nature of Christian change by examining Ephesians 4. 

The book of Ephesians follows the typical pattern of the letters of the New Testament. The first part of the letter contains theology and the second section ends with applications. As seminary students are wont to say the imperative follows the indicative. We see this in the book of Ephesians.

Starting with chapter four, the book of Ephesians lays out the implications of the work of Christ in concrete ways. The one who speaks falsehood must now speak the truth (4:26), the one who steals must now commit to honest work to help those in need (4:28), the one whose mouth is unwholesome must begin to speak words of encouragement (4:29), and the one who is filled with bitterness and malice ought now to forgive and show compassion (4:31, 32). These commands are important and practical at face value, but there is an important theological assumption to consider.

Within the Christian framework, it is not simply good enough to stop with unwanted and harmful behavior. Christianity states that there must also be positive fruit. More importantly, it is the positive fruits that are the evidence that the pattern of sin is broken. In short, fruitfulness presupposes a good heart. Apart from fruitfulness, there is no proof that the heart has changed.

This is exactly why Paul does not simply say that the thief should stop stealing. This is not good enough. The thief, to show transformation, must begin to labor and share with others. If an ex-thief can do this, he or she has changed! The fruit is the proof. Similarly, it is not good enough that a person put an end to unwholesome talk; he or she must also speak words of encouragement and life.  And again it is the latter that speaks of the transformation of the heart.

This logic is helpful in at least two ways. First, it forces people to deal with the heart of the matter (literally). This framework reminds us that sin is not merely a matter of actions, but the heart. Second, it shows people what a good heart produces, namely, good fruit.