What is Faith?

Q. 21: What is true faith?

A.: True faith is not only a sure knowledge whereby I hold for truth all that God has revealed to us in his Word, but also a hearty trust, which the Holy Spirit works in me by the Gospel, that not only to others, but to me also, forgiveness of sins, everlasting righteousness, and salvation are freely given by God, merely of grace, only for the sake of Christ’s merits.

- From the Heidelberg Catechism