Salvation By Knowing The Truth pt.5 - Spurgeon

Moreover, it often happens that a knowledge of the truth stands a man in good stead for another purpose; it saves him from despair. Unable to be careless, and unable to find comfort in false confidences, some poor agitated minds are driven into a wide and stormy sea without rudder or compass, with nothing but wreck before them. "There is no hope for me," says the man. "I perceive I cannot save myself. I see that I am lost. I am dead in trespasses and sins, and cannot stir hand or foot. Surely now I may as well go on in sin, and even multiply my transgressions. The gate of mercy is shut against me; what is the use of fear where there is no room for hope?" At such a time, if the Lord leads the man to a knowledge of the truth, he perceives that though his sins be as scarlet they shalt be as wool, and though they be red like crimson they shall be as white as snow. That precious doctrine of substitution comes in—that Christ stood in the stead of the sinner, that the transgression of his people was laid upon him, and that God, by thus avenging sin in the person of his dear Son, and honoring his law by the suffering of the Savior, is now able to declare pardon to the penitent and grace to the believing. Now, when the soul comes to know that sin is put away by the atoning blood; when the heart discovers that it is not our life that saves us, but the life of God that comes to dwell in us; that we are not to be regenerated by our own actions, but are regenerated by the Holy Ghost who comes to us through the precious death of Jesus, then despair flies away, and the soul cries exultingly, "There is hope. There is hope. Christ died for sinners: why should I not have a part in that precious death? He came like a physician to heal the sick: why should he not heal me? Now I perceive that he does not want my goodness, but my badness; he does not need my righteousness, but my unrighteousness: for he came to save the ungodly and to redeem his people from their sins. I say, when the heart comes to a knowledge of this truth, then it is saved from despair; and this is no small part of the salvation of Jesus Christ.
A saving knowledge of the truth, to take another line of things, works in this way. A knowledge of the truth shows a man his personal need of being saved. O you that are not saved, and who dream you do not need to be, you only require to know the truth, and you will perceive that you must he saved or lost for ever.