It is in Paul’s letters that the meaning of faith is most clearly and fully set forth. In essence, faith is trust in the person of Jesus, the truth of his teaching, and the redemptive work he accomplished at Calvary, and, as a result, a total submission to him and his message, which are accepted as from God. Faith in his person is faith in him as the eternal Son of God who died in the sinner’s stead, making possible justification with God, adoption into his family, sanctification, and ultimately, glorification upon our death.
His death brings redemption from sin in all of its aspects, which is verified when God raised Jesus from the dead.
Faith is NOT an intellectual assent to Christianity albeit this is necessary. Faith is a radical and total commitment to Christ as the Lord of one’s own life.
Unbelief or lack of faith in the Christian gospel, appears everywhere in the New Testament as the supreme evil. Not to make a decisive response to God’s offer in Christ means an individual remains in sin and is eternally lost. Faith alone saves.
Taken from Zondervan’s Illustrated Bible Dictionary by J.D. Douglas and Merrill C Tenney