Whenever a sinner is converted to God, distinct motions, or movements, occur in his heart. In the first place, alarmed on account of his sins, which the divine Law has made known to him, Rom. 3, 20, he experiences the terrors of conscience (terrores conscientiae), that is, true fear and anguish of heart. Acts 16, 29. 30. The terrors of conscience (terrores incussi conscientiae agnito peccato), though necessary, are not meritorious in themselves, Matt. 27, 3—5. In spite of his knowledge of sin and the wrath of God the alarmed sinner, as long as he hears nothing of the Gospel, remains unconverted. However, when the Gospel is preached to him, the Holy Spirit engenders in his heart true faith (fiducia cordis) in the gracious promises of forgiveness, and it is through this second motion, that is, through implicit trust in Christ, that he is converted, Acts 16, 31—34.
These two motions, contrition and faith, are found in every person who is truly converted, Ps. 32,1—5. Where they do not occur, genuine conversion has not taken place.
The Formula of Concord writes (Thor. Decl., II, 70): “In genuine conversion a change, new emotion, and movement in the intellect, will, and heart must take place, namely, that the heart perceive sin, dread God’s wrath, turn from sin, perceive and accept the promise of grace in Christ, have good spiritual thoughts, a Christian purpose and diligence, and strive against the flesh. For where none of these occurs or is present, there is also no true conversion ."
However, where contrition and faith are present in the heart,, there conversion has taken place, even though the believer’s knowledge of sin and his trust in divine grace are yet weak. Scripture nowhere demands a specific degree of contrition or faith, though,, of course, the regenerate should strive to grow in knowledge of both sin and grace, Col. 1, 9—11; 2 Pet. 3, 18. True contrition may be said to exist in every case where a penitent sinner regards- himself as eternally lost on account of his sins, Acts 16, 30.
True love of God is not a part of contrition; love is a fruit of faith, Gal. 5, 22, or the effect of conversion. But saving faith exists in the heart as soon as the penitent sinner longs for, or desires, divine grace in Christ Jesus, that is to say, as soon as he has a mere spark of faith (scintillula fidei), as Holy Scripture clearly teaches. Is. 42, 3; Mark 9, 24. The Formula of Concord says (Thor. Decl.,. II, 14): “To all godly Christians who feel and experience in their hearts a small spark or longing for divine grace and eternal salvation this precious passage Phil. 2, 13 is very comforting; for they know that God has kindled in their hearts this beginning of true godliness and that He will further strengthen and help them in their great weakness to persevere in true faith unto the end.”