Chapter 24: Lord's Day 24
Section 62. Q. 62: But why can't the good we do make us right with God, or at least help make us right with him? A. Because the righteousness which can pass God's judgment must be entirely perfect and must in every way measure up to the divine law. Even the best we do in this life is imperfect and stained with sin.
Section 63. Q. 63: How can you say that the good we do doesn't earn anything when God promises to reward it in this life and the next? A. This reward is not earned; it is a gift of grace.
Section 64. Q. 64: But doesn't this teaching make people indifferent and wicked? A. No. It is impossible for those grafted into Christ by true faith not to produce fruits of gratitude.