The Heidelberg Catechism Part II: Deliverance Lord’s Day 7
Question 20: Are all people then saved through Christ just as they were lost through Adam?
Answer 20: No. Only those are saved who through true faith are grafted into Christ and accept all His benefits. 
 Matthew 7:14 NKJV Because narrow is the gate and difficult is the way which leads to life, and there are few who find it.
John 3:16 NKJV For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life.
John 3:18 NKJV "He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God.
John 3:36 NKJV He who believes in the Son has everlasting life; and he who does not believe the Son shall not see life, but the wrath of God abides on him."
Romans 11:16-21 NKJV For if the firstfruit is holy, the lump is also holy; and if the root is holy, so are the branches. (17) And if some of the branches were broken off, and you, being a wild olive tree, were grafted in among them, and with them became a partaker of the root and fatness of the olive tree, (18) do not boast against the branches. But if you do boast, remember that you do not support the root, but the root supports you. (19) You will say then, "Branches were broken off that I might be grafted in." (20) Well said. Because of unbelief they were broken off, and you stand by faith. Do not be haughty, but fear. (21) For if God did not spare the natural branches, He may not spare you either.
Q21: What is true faith?
A21: True faith is not only a sure knowledge by which I hold as true all that God has revealed to us in Scripture;  it is also a wholehearted trust,  which the Holy Spirit creates in me  by the gospel,  that God has freely granted, not only to others but to me also,  forgiveness of sins, eternal righteousness, and salvation.  These are gifts of sheer grace, granted solely by Christ’s merit. 
 John 17:3 NKJV And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent.
John 17:17 NKJV Sanctify them by Your truth. Your word is truth.
Hebrews 11:1-3 NKJV Now faith is the substance of things hoped for, the evidence of things not seen. (2) For by it the elders obtained a good testimony. (3) By faith we understand that the worlds were framed by the word of God, so that the things which are seen were not made of things which are visible.
James 2:19 NKJV You believe that there is one God. You do well. Even the demons believe – and tremble!
 Romans 4:18-21 NKJV who, contrary to hope, in hope believed, so that he became the father of many nations, according to what was spoken, "SO SHALL YOUR DESCENDANTS BE." (19) And not being weak in faith, he did not consider his own body, already dead (since he was about a hundred years old), and the deadness of Sarah's womb. (20) He did not waver at the promise of God through unbelief, but was strengthened in faith, giving glory to God, (21) and being fully convinced that what He had promised He was also able to perform.
Romans 5:1 NKJV Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ,
Romans 10:10 NKJV For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation.
Hebrews 4:14-16 NKJV Seeing then that we have a great High Priest who has passed through the heavens, Jesus the Son of God, let us hold fast our confession. (15) For we do not have a High Priest who cannot sympathize with our weaknesses, but was in all points tempted as we are, yet without sin. (16) Let us therefore come boldly to the throne of grace, that we may obtain mercy and find grace to help in time of need.
 Matthew 16:15-17 NKJV He said to them, "But who do you say that I am?" (16) Simon Peter answered and said, "You are the Christ, the Son of the living God." (17) Jesus answered and said to him, "Blessed are you, Simon Bar-Jonah, for flesh and blood has not revealed this to you, but My Father who is in heaven.
John 3:5 NKJV Jesus answered, "Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God.
Acts 16:14 NKJV Now a certain woman named Lydia heard us. She was a seller of purple from the city of Thyatira, who worshiped God. The Lord opened her heart to heed the things spoken by Paul.
 Acts 16:14 NKJV Now a certain woman named Lydia heard us. She was a seller of purple from the city of Thyatira, who worshiped God. The Lord opened her heart to heed the things spoken by Paul.
Acts 10:17 NKJV Now while Peter wondered within himself what this vision which he had seen meant, behold, the men who had been sent from Cornelius had made inquiry for Simon's house, and stood before the gate.
1 Corinthians 1:21 NKJV For since, in the wisdom of God, the world through wisdom did not know God, it pleased God through the foolishness of the message preached to save those who believe.
 Galatians 2:20 NKJV I have been crucified with Christ; it is no longer I who live, but Christ lives in me; and the life which I now live in the flesh I live by faith in the Son of God, who loved me and gave Himself for me.
 Romans 1:17 NKJV For in it the righteousness of God is revealed from faith to faith; as it is written, "The just shall live by faith."
Hebrews 10:10 NKJV By that will we have been sanctified through the offering of the body of Jesus Christ once for all.
 Romans 3:21-26 NKJV But now the righteousness of God apart from the law is revealed, being witnessed by the Law and the Prophets, (22) even the righteousness of God, through faith in Jesus Christ, to all and on all who believe. For there is no difference; (23) for all have sinned and fall short of the glory of God, (24) being justified freely by His grace through the redemption that is in Christ Jesus, (25) whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed, (26) to demonstrate at the present time His righteousness, that He might be just and the justifier of the one who has faith in Jesus.
Galatians 2:16 NKJV knowing that a man is not justified by the works of the law but by faith in Jesus Christ, even we have believed in Christ Jesus, that we might be justified by faith in Christ and not by the works of the law; for by the works of the law no flesh shall be justified.
Ephesians 2:8-10 NKJV For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, (9) not of works, lest anyone should boast. (10) For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them.
Q22: What then must a Christian believe?
A22: All that is promised us in the gospel,  a summary of which is taught us in the articles of our universal and undisputed Christian faith.
 Matthew 28:18-20 NKJV And Jesus came and spoke to them, saying, "All authority has been given to Me in heaven and on earth. (19) Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, (20) teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age." Amen.
John 20:30-31 NKJV And truly Jesus did many other signs in the presence of His disciples, which are not written in this book; (31) but these are written that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in His name.
Q23: What are these articles?
A23: I believe in God, the Father almighty, creator of heaven and earth. I believe in Jesus Christ, His only begotten Son, our Lord, who was conceived by the Holy Spirit and born of the virgin Ma He suffered under Pontius Pilate, was crucified, died, and was buried; he descended to hell. The third day He rose again from the dead. He ascended to heaven and is seated at the right hand of God the Father almighty. From there He will come to judge the living and the dead. I believe in the Holy Spirit, the holy catholic [i.e., universal] church, the communion of saints, the forgiveness of sins, the resurrection of the body, and the life everlasting. Amen.