"But to one who without works trusts him who justifies the ungodly, such faith is reckoned as righteousness. Romans 4:5.
Faith tells you that the whole virtue and power of Christ's blood, by which the world was redeemed, is offered to you. And He personally brings it to you. Christ does not ration out His blood, some to one and some to another; but He gives His whole self to the faith of every believer. You belong to the Redeemer. And He is yours. Faith opposes despair.
The greatest command in the whole Bible is to believe. When the Jews asked our Lord Jesus, "What shall we do, that we might work the works of God?" notice His reply: "This is the work of God, that ye believe on him whom he hath sent" (John 6:28-29). It is as if He ha said, "Receive me into your hearts by faith; do this, and you do it all." This is the all in all. Everything you do is futile until this work is done; but when you have believed, God appreciates it as much as if you had kept the whole law. In fact, it is accepted in lieu of it: But to one who without works trusts him who justifies the ungodly, such faith is reckoned as righteousness. Romans 4:5.
This man's faith in Christ is accepted for righteousness; that is, at the judgment he will escape the sentence as is he had never strayed a step from the path of the law. If faith is the work of God above all other, then unbelief is the work of the devil. He works harder to make men unbelievers than drunkards or murderers. And despair is unbelief at its worst. Unbelief among sins is as the plague among diseases, the most dangerous; but when it settles into despair, then it is like the plague, which brings certain death with it. Unbelief is despair in the bud, but despair is unbelief at its full growth.
Every sin wounds the law and the name of God. But this wound is healed when the penitent sinner by faith comes to Christ and unites with Him. And through Christ God receives the sinner in the fullness of righteousness and vindicates His own name.”
Quoted material from, ”The Christian in Complete Armour Daily Readings in Spiritual Warfare” by Gurnall and James S Bell. http://www.moodypublishers.com/pub_productDetail.aspx?id=41823&pid=53617