Q. 20. Are all men then, as they perished in Adam, saved by Christ?
No: only those who are ingrafted into Him, and receive all His benefits, by a true faith.
 Matthew 1:21; Isaiah 53:11;  John 1:12–13; Romans 11:20; Hebrews 10:39.
Q. 21. What is true faith?
True faith is not only a certain knowledge, whereby I hold for truth all that God has revealed to us in His Word, but also an assured confidence, which the Holy Ghost works by the gospel, in my heart, that not only to others, but to me also, remission of sin, everlasting righteousness and salvation, are freely given by God, merely of grace, only for the sake of Christ’s merits.
 John 6:69; John 17:3; Hebrews 11:3, 6;  Ephesians 3:12;  Romans 4:16, 20–21; Hebrews 11:1; Ephesians 3:12; Romans 1:16; 1 Corinthians 1:21; Acts 16:14; Matthew 16:17; John 3:5;  Romans 10:14, 17; Matthew 9:2;  Romans 5:1;  Galatians 2:20;  Romans 3:24–26.
Q. 22.What is then necessary for a Christian to believe?
All things promised us in the gospel, which the articles of our catholic undoubted Christian faith briefly teach us.
 John 20:31; Matthew 28:19–20.
Q. 23. What are these articles?
Although all men are fallen, not all men will be saved by Christ, but only such as have been elected in Him, who would in due time be united with Him by faith. Saving faith involves knowing (notitia), believing (assensus) and trusting (fiducia) in the Lord Jesus Christ. Since the natural man is spiritually blinded and dead in sin, only those whom God purposed (in election and predestination) to be united with Christ will have faith. This faith is a gift of God (Eph 2:8–9). It is not something self-generated. It is God-given, firstly, because God reveals what we are to believe, secondly, God convicts us as to the truth of what is revealed, and thirdly, He changes our hearts in the new birth so that we trust in Christ wholeheartedly.
Heidelberg Catechism >