A foundational truth of biblical Christianity is that the believer has a right standing before God in the gospel-in Christ alone. The psalms of David confront us with man's greatest dilemma: "Who may ascend into the hill of the Lord? Or who may stand in His holy place? He who has clean hands and a pure heart who has not lifted up his soul to an idol, nor sworn deceitfully." Any man who entertains even the remotest possibility that there is a personal and moral God must tremble at David's question. Unless he is an imbecile or his conscience has been seared beyond use, he must recognize that he does not possess the necessary qualifications to stand approved before the Judge of all the earth. The Scriptures tell us that if he looks within, he will find that his heart is more deceitful than all else and is wicked beyond comprehension. If he turns to consider his own mind, he will find that there are wicked thoughts lodged within. If he listens intently to his speech, he will become aware that it is full of deceit, cursing, and bitterness. If he gazes upon his hands, he will see that they are stained with the residue of countless misdeeds. If in desperation he seeks to cover his shame by dressing himself in his most righteous deeds, he will find that he is clothed in the filthy rot of a leper. Although he washes himself with lye and uses much soap, the stain of his iniquity remains. Everywhere he turns, he finds himself accused, condemned, and without hope. It is in this moment of absolute helplessness and final resignation that the illumined and regenerate sinner looks to Christ and finds his hope in Him. Turning from self-righteousness, he believes and is justified by grace alone through faith alone. From that moment on, he bears the twin marks of a Christian: he glories in Christ Jesus and puts no confidence in the flesh. He has entered into that great company of saints who believed God and it was reckoned to them as righteousness. He has cast himself upon Christ and clings to Him with a strength multiplied by the terror of what would have befallen him if he had been left to fend for himself. He stands upon Christ alone and will not venture from Him. He is convinced that he can ascend into the hill of the Lord and stand in His holy place only by virtue of the person and merit of Christ. To paraphrase the old hymn writer: "His hope is built on nothing less than Jesus' blood and righteousness. He dare not trust the sweetest frame, but wholly lean on Jesus' name. On Christ the solid Rock he stands, all other ground is sinking sand; all other ground is sinking sand."
~Paul Washer in his book The Gospel's Power & Message, chapter 2 pages 13-14