Good works are not optional for the Christian. We must do good, not as the means of our acceptance with God, but as an expression of it. In the lifelong pursuit of holiness, we would do well to consider all the biblical motivations for Christlikeness. For at one time or another, we will need them all. And so will the people God brings before us in need of similar transformation.

Good question.

It’s a question Catholics have often asked Protestants as they wax on about justification by faith alone. It’s a question I’ve had posed to me, in one way or another, by both Muslims and Mormons. It’s a question that even Gospel-centered Christians don’t always seem to agree on.

Thankfully, it’s also a question we find in the Heidelberg Catechism (Q/A 86).

According to the Catechism, there are at least five reasons we who have been saved by grace alone through faith alone must still do good.

1. Fruit. Good works are the fruit of which justification is the root. If we have the grace of God inside us we will have something of the grace showing through to the outside. “Christ by his Spirit is also renewing us to be like himself.”

2. Gratitude. Good works show to God and to the world that we have much to be thankful for (Rom. 6:13; 12:1-2; 1 Pet. 2:5-10). When we are grateful, the nastiness of vice and pride is pushed aside. In its place we consider all that God has done for us and instinctively–and supernaturally–aim to please the one who has shown us such mercy.

3. Glory. Good works testify that God is worthy of our obedience and service (Matt. 5:16; 1 Cor. 6:19-20). He receives praise when people see his reflection in us. His majesty is magnified when others recognize that we consider him a God to be feared and a Father to be loved.

4. Assurance. Good works bear witness to our own hearts that we are children of God (Matt. 7:17-18; Gal. 5:22-24; 2 Pet. 1:10-11). As we spot good fruit growing in our lives, we should conclude that we, therefore, cannot be bad trees.

5. Conversion. Good works make our neighbors stand up and take notice (Matt. 5:14-16; Rom. 14:17-19; 1 Pet. 2:12; 3:1-2). Our behavior cannot, by itself, win sinners to Christ. But our good works can adorn the gospel and lead the lost to consider whether they are as found as they thought.

Good works are not optional for the Christian. We must do good, not as the means of our acceptance with God, but as an expression of it. In the lifelong pursuit of holiness, we would do well to consider all the biblical motivations for Christlikeness. For at one time or another, we will need them all. And so will the people God brings before us in need of similar transformation.

Kevin DeYoung has been the Senior Pastor at University Reformed Church (RCA) in East Lansing, Michigan since 2004. Kevin blogs at the Gospel Coalition; this article is reprinted with his permission.