Kevin DeYoung wrestles with the question, "why then must we still do good?"
Q. We have been delivered from our misery by God’s grace alone through Christ and not because we have earned it: why then must we still do good?
A. To be sure, Christ has redeemed us by his blood. But we do good because Christ by his Spirit is also renewing us to be like himself, so that in all our living we may show that we are thankful to God for all he has done for us, and so that he may be praised through us. And we do good so that we may be assured of our faith by its fruits, and so that by our godly living our neighbors may be won over to Christ. (Heidelberg Catechism Q/A 86)
One of the common objections to the Christian view of salvation, especially in its Reformed expression, is that salvation by grace alone through faith alone leads to moral license. If we can’t earn one tiny iota of deliverance from sin by our good works, then why do good at all?
The Heidelberg Catechism gives five reasons why those in Christ must still do good.
First, we do good because the Holy Spirit is working in us to make us more like Jesus (2 Cor. 3:18). The same Spirit who caused us to be born again and enabled us to believe will also work to make us holy (Rom. 6:9-11).
Second, we do good out of gratitude (Rom. 12:1-2). This is not to suggest that God saves us and then we work the rest of our lives to pay him back for the favor (Rom. 11:33-36). Rather, we do good because the wonder of our salvation produces such thankfulness in our hearts that it is our pleasure to serve God.
Third, we do good so that God might be praised by the works we display in his name. “By this my Father is gloried,” Jesus said, “that you bear much fruit and so prove to be my disciples” (John 15:8).
Fourth, we do good so that we can be assured of our right standing before God. Faith alone justifies, but the faith that justifies is never alone. By bearing good fruit, we show that we are a good tree (Matt. 7:15-20) and make our calling and election sure (2 Peter 1:10).
Fifth, we do good in order that we might adorn the gospel (Titus 2:10) and make it attractive to outsiders (1 Peter 2:12).
Clearly, the Bible is not indifferent to good works. Christians who live in habitual, unrepentant sin show themselves not to be true Christians. Of course, we all stumble (James 3:2; 1 John 1:8). But there’s a difference between falling into sin and jumping in with both feet. It doesn’t matter the sin—pride, slander, robbery, covetousness, or sexual immorality—if we give ourselves to it and live in it with joyful abandon, we will not inherit the kingdom of God. Simply put, people walking day after day in the same sin without a fight or repentance go to hell (1 Cor. 6:9-10; Gal. 5:19-21; 1 John 3:14). And on the flip side, people walking day after day in the light of the gospel and in view of their union with Christ, will–imperfectly, but truly–learn to do good, be good, and get better.