Lord's Day 7: What is Saving Faith in Christ?

Heidelberg Catechism LORD'S DAY 7

20. Are all men, then, saved by Christ as they have perished in Adam?
    No, only those who by true faith are ingrafted into Him and receive all His benefits (John 1:12-13;1 Cor. 15:22; Ps. 2:12; Rom. 11:20; Heb. 4:2-3; Heb. 10:39).

21. What is true faith?
    True faith is not only a sure knowledge, whereby I hold for truth all that God has revealed to us in His Word (James 1:6), but also a hearty trust (Rom. 4:16-18; Rom. 5:1), which the Holy Ghost (2 Cor. 4:13; Phil. 1:19, 29) works in me by the Gospel (Rom. 1:16; 10:17), that not only to others, but to me also, forgiveness of sins, everlasting righteousness, and salvation are freely given by God (Heb. 11:1-2; Rom. 1:17), merely of grace, only for the sake of Christ's merits (Eph. 2:7-9; Rom. 3:24-25; Gal. 2:16; Acts 10:43).

22. What, then, is necessary for a Christian to believe?
    All that is promised us in the Gospel (John 20:31; Matt. 28:20), which the articles of our catholic, undoubted Christian faith teach us in summary.

23. What are these articles?
    I believe in God the Father Almighty, Maker of heaven and earth.
    And in Jesus Christ, His only begotten Son, our Lord: who was conceived by the Holy Ghost, born of the virgin Mary, suffered under Pontius Pilate, was crucified, dead, and buried; He descended into hell; the third day He rose from the dead; He ascended into heaven, and sitteth at the right hand of God the Father Almighty; from thence He shall come to judge the living and the dead.
    I believe in the Holy Ghost, the Holy Catholic Church, the communion of saints, the forgiveness of sins, the resurrection of the body, and the life everlasting.