The Heidelberg Catechism: Lord's Day 32
Question 86. Since then we are delivered from our misery, merely of grace, through Christ, without any merit of ours, why must we still do good works?
Answer: Because Christ, having redeemed and delivered us by his blood, also renews us by his Holy Spirit, after his own image; that so we may testify, by the whole of our conduct, our gratitude to God for his blessings, (a) and that he may be praised by us; (b) also, that every one may be assured in himself of his faith, (c) by the fruits thereof; and that, by our godly conversation others may be gained to Christ. (d)
(a) Rom.6:13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God. Rom.12:1 I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. Rom.12:2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and
perfect, will of God. 1 Pet.2:5 Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ. 1 Pet.2:9 But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvelous light: 1 Pet.2:10 Which in time past were not a people, but are now the people
of God: which had not obtained mercy, but now have obtained mercy. 1 Cor.6:20 For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God’s. (b) Matt.5:16 Let your light so shine before men, that they may see your good works, and glorify your Father which is in heaven. 1 Pet.2:12 Having your conversation honest among the Gentiles: that, whereas they speak against you as evildoers, they may by your good works, which they shall behold, glorify God in the day of visitation. 1 Pet.1:6 Wherein ye greatly rejoice, though now for a season, if need be, ye are in heaviness through manifold temptations: 1 Pet.1:7 That the trial of your faith, being much more precious than of gold that perisheth, though it be tried with fire, might be found unto praise and honour and glory at the appearing of Jesus Christ: (c) 2 Pet.1:10 Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall: Matt.7:17 Even so
every good tree bringeth forth good fruit; but a corrupt tree bringeth forth evil fruit. Gal.5:6 For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith which worketh by love. Gal.5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, Gal.5:23 Meekness, temperance: against such there is no law. (d) 1 Pet.3:1 Likewise, ye wives, be in subjection to your own husbands; that, if any obey not the word, they also may without the word be won by the conversation of the wives; 1 Pet.3:2 While they behold your chaste conversation coupled with fear. Rom.14:19 Let us therefore follow after the things which make for peace, and things wherewith one may edify another.
Question 87. Cannot they then be saved, who, continuing in their wicked and ungrateful lives, are not converted to God?
Answer: By no means; for the holy scripture declares that no unchaste person, idolater, adulterer, thief, covetous man, drunkard, slanderer, robber, or any such like, shall inherit the kingdom of God. (a)
(a) 1 Cor.6:9 Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind, 1 Cor.6:10 Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God. Eph.5:5 For this ye know, that no whoremonger, nor unclean person, nor covetous man, who is an idolater, hath any inheritance in the kingdom of Christ and of God. Eph.5:6 Let no man deceive you with vain words: for because of these things cometh the wrath of God upon the children of disobedience. 1 John 3:14 We know that we have passed from death unto life, because we love the brethren. He that loveth not his brother abideth in death.
The Heidelberg Catechism: Lord's Day 31
83. Question: What are the keys of the kingdom of heaven?
Answer: The preaching of the holy gospel and church discipline. By these two the kingdom of heaven is opened to believers and closed to unbelievers.
 Matt. 16:19; John 20:21-23.
84. Question: How is the kingdom of heaven opened and closed by the preaching of the gospel?
Answer: According to the command of Christ, the kingdom of heaven is opened when it is proclaimed and
publicly testified to each and every believer that God has really forgiven all their sins for the sake of Christ's merits, as often as they by true faith accept the promise of the gospel. The kingdom of heaven is closed when it is proclaimed and testified to all unbelievers and hypocrites that the wrath of God and eternal condemnation rest on them as long as they do not repent. According to this testimony of the gospel, God will judge both in this life and in the life to come.
 Matt. 16:19; John 3:31-36; 20:21-23.
85. Question: How is the kingdom of heaven closed and opened by church discipline?
Answer: According to the command of Christ, people who call themselves Christians but show themselves to be unchristian in doctrine or life are first repeatedly admonished in a brotherly manner. If they do not give up their errors or wickedness, they are reported to the church, that is, to the elders. If they do not heed also their admonitions, they are forbidden the use of the sacraments, and they are excluded by the elders from the Christian congregation, and by God Himself from the kingdom of Christ. They are again received as members of Christ and of the church when they promise and show real amendment.
 Matt. 18:15-20; I Cor. 5:3-5; 11-13; II Thess. 3:14, 15.  Luke 15:20-24; II Cor. 2:6-11.
The Heidelberg Catechism: Lord's Day 24
62. Question: But why can our good works not be our righteousness before God, or at least a part of it?
Answer: Because the righteousness which can stand before God's judgment must be absolutely perfect and in complete agreement with the law of God, whereas even our best works in this life are all imperfect and defiled with sin.
 Deut. 27:26; Gal. 3:10.  Is. 64:6.
63. Question: But do our good works earn nothing, even though God promises to reward them in this life and the next?
Answer: This reward is not earned; it is a gift of grace.
 Matt. 5:12; Heb. 11:6.  Luke 17:10; II Tim. 4:7, 8.
64. Question: Does this teaching not make people careless and wicked?
Answer: No. It is impossible that those grafted into Christ by true faith should not bring forth fruits of
 Matt. 7:18; Luke 6:43-45; John 15:5.
The Heidelberg Catechism
Lord's Day 1