The Heidelberg Catechism Part II: Deliverance Righteousness of Christ, Part 2 Lord’s Day 24
Question 62: Why can’t our good works be our righteousness before God, or at least a part of our righteousness?
Answer 62: Because the righteousness which can pass God’s judgment must be entirely perfect and must in every way measure up to the divine law.  But even our best works in this life are imperfect and stained with sin. 
 Romans 3:20 NKJV Therefore by the deeds of the law no flesh will be justified in His sight, for by the law is the knowledge of sin.
Galatians 3:10 NKJV (Deut. 27:26) For as many as are of the works of the law are under the curse; for it is written, "Cursed is everyone who does not continue in all things which are written in the book of the law, to do them."
 Isaiah 64:6 NKJV But we are all like an unclean thing, And all our righteousnesses are like filthy rags; We all fade as a leaf, And our iniquities, like the wind, Have taken us away.
Q 63: How can our good works be said to merit nothing when God promises to reward them in this life and the next? 
A 63: This reward is not earned; it is a gift of grace. 
 Matthew 5:12 NKJV Rejoice and be exceedingly glad, for great is your reward in heaven, for so they persecuted the prophets who were before you.
Hebrews 11:6 NKJV But without faith it is impossible to please Him, for he who comes to God must believe that He is, and that He is a rewarder of those who diligently seek Him.
 Luke 17:10 NKJV So likewise you, when you have done all those things which you are commanded, say, 'We are unprofitable servants. We have done what was our duty to do.' "
2 Timothy 4:7-8 NKJV I have fought the good fight, I have finished the race, I have kept the faith. (8) Finally, there is laid up for me the crown of righteousness, which the Lord, the righteous Judge, will give to me on that Day, and not to me only but also to all who have loved His appearing.
Q 64: But doesn’t this teaching make people indifferent and wicked?
A 64: No. It is impossible for those grafted into Christ through true faith not to produce fruits of gratitude. 
 Luke 6:43-45 NKJV "For a good tree does not bear bad fruit, nor does a bad tree bear good fruit. (44) For every tree is known by its own fruit. For men do not gather figs from thorns, nor do they gather grapes from a bramble bush. (45) A good man out of the good treasure of his heart brings forth good; and an evil man out of the evil treasure of his heart brings forth evil. For out of the abundance of the heart his mouth speaks.
John 15:5 NKJV "I am the vine, you are the branches. He who abides in Me, and I in him, bears much fruit; for without Me you can do nothing.