What is the danger / consequence of unconfessed sin?

There is no such thing, in dealing with God, as covering up sin. "He that covereth his sins shall not prosper" (Prov. 28:13), and God only deals with men on the basis of what they are. If a man comes to God claiming to be righteous, God must refuse him: "The proud He knoweth afar off" (Ps. 138:6). The Pharisee and publican teach us this. He will only meet in grace those whom His holiness has already convicted of sin. So our Lord, the bearer of God's message of love to the world, was ever the Prophet; the garment of goats' hair did not misbecome Him who in divine grace came to seek and to save the lost.

An important message is contained in verse 13. "He that covereth his sins shall not prosper; but whoso confesseth and forsaketh them shall have mercy." Every attempt to cover up sin is a failure. How much of this is done today, not merely the covering of individual sins, but the denial of sin itself. The modern theology useth much ingenious argumentation which tries to make out of sin something else; speaks of it as a mere defect, as if it were some kind of a taint in the blood, a hereditary and therefore unavoidable weakness, something for which man is not responsible. All these inventions, which sweep aside the declarations of the infallible Word of God, are "covering up." No mercy can there be for those who deny sin and sins. The fig leaves must be torn away with which man still tries to cover his nakedness. There must be confession, repentance, self-judgment and then of course trust in Him who died for the ungodly.

"He that covereth his sins shall not prosper: but who-so confesseth and forsaketh them shall have mercy."

This is an unalterable, Divine principle, applicable in the first place to the salvation of the soul, and just as applicable to the conduct of a believer. If a sinner deceitfully covers up his guilt, he can expect no mercy from God, no prospering, but eternal judgment. If he honestly confesses his sins, having faith in the blessed Son of God, then mercy forgives him, and for eternity. On the other hand, if one is a true believer, but walks in disobedience to God, seeking to cover up his wrongdoing, God will not allow him to prosper in his Christian path: he will suffer. But if he honestly confesses his wrongs to his God and Father, then he will prove the sweetness of God's mercy as his present experience.

It is good when God acts similarly with us, as indeed He often does. He that covereth his sin shall not prosper (Prov. 28:13); and if we will not voluntarily confess our sin, it is good that God should use His own means to force that sin into the open; for only then can He bring blessing to us. "When I kept silence, my bones waxed old, through my groaning all the day long. For day and night Thy hand was heavy upon me; my moisture was turned into the drought of summer. Selah. I acknowledged my sin unto Thee, and mine iniquity I covered not; I said, I will confess my transgression unto Jehovah, and THOU forgavest the iniquity of my sin. Selah." (Ps. 32:3-5)

Unbelieving men would make Israel's plight a ground of complaint and reproach against God. Either He was indifferent so that His ear never caught their cries, or He was impotent and unable to deliver them. The true state of the case was that their sins had driven a wedge of separation between them and God. They were utterly alienated from Him.

This is a matter that some of us are inclined to overlook. In considering the havoc sin has wrought we are apt to think mainly of the guilt of our sins and the judgment they will incur; perhaps also thinking of the enslaving power exerted by sin in our lives, while giving but little thought to the way in which it has separated us from God. But none of the effects of sin is more disastrous than this — alienation.

So long as Israel's sin remained unconfessed, it remained unforgiven, and consequently they had no strength to war for Jehovah. He was not with them, for the sin in their camp had separated between them and their God (Isa. 59:2); but having now confessed and forsaken their sin, God had put it away. Some of God's people spend months — nay, years — of their lifetime in a condition of spiritual inaction, their hearts like water, and themselves afar from the knowledge of God's mind! Let there be but the breadth of a hair severing the telegraphic line of communication between this country and America, and we cannot hold intercourse with our friends across the ocean. Thus does sin separate between God and His people. Not indeed that God foregoes His grace towards His own, or fails to bring them safely home; but here on earth, during this lifetime, unconfessed sin breaks into the communication of God's mind to us, and to it is due the absence of divine power in us, and hence ineffective soldiership.

The priesthood of Christ comes in to maintain me practically where the blood of Christ has set me. As in the expression in the Epistle of John, "If any man sin, we have an advocate with the Father, Jesus Christ the righteous [Jesus Christ is at God's right hand on all principles of righteousness], and He is the propitiation [the mercy-seat] for our sins." "If we confess our sins, He is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness." It is a much easier thing for a child to ask for pardon for some fault than to confess it. We may be asking for pardon for any special sin, and we have no Scripture warrant to know that it is put away; but when we confess it, it is a matter of faith to know that it is put away. I am speaking now of a believer: were it the question of an unconverted person, the blood of Christ meets that. God is "faithful and just (not gracious and merciful merely), to forgive us our sins," etc. The moment I have judged myself about it, I am entitled to know that it is gone.

1 John 1:9. Having a sinful nature, the fruits of it manifest themselves, even in the Christian, when he is not walking in communion with God. But our sins are not to be covered up; they are to be confessed. Coming in confession to God, we learn that He is faithful and righteous to forgive. We can have the fullest confidence in God: His faithfulness is known in the forgiveness we receive. With each other, we may be very slow to forgive, and very grudgingly pardon those who confess to us their wrongdoings. But God is faithful in His forgiving; we can come to Him perfectly assured that He will forgive, if we confess our sins. Without the confession, the guilt lies upon the conscience, and the defilement on the spirit. Forgiveness on God's part is also a righteous thing, and this because of the work of the cross. God could not pardon the sinner in righteousness apart from the work of Christ; therefore His forgiving of sins magnifies the great work of propitiation accomplished by the Lord Jesus. Then there is the cleansing from all unrighteousness. Unrighteousness in the Christian calls for confession, not only that we might have the sense of Gods pardon, but also that the defilement produced on the spirit might be removed. This is not cleansing by a fresh application of the blood to the believer, but is produced through the action of the word of God on the defiled spirit. Our first coming to God as guilty sinners could not rightly be excluded from this verse; its abstract nature leaves room for this; but it is good for us as failing Christians at all times.

Not only does He forgive, but He also cleanses from all unrighteousness. The honest confession of sin by the saint not only ensures forgiveness but it also has a cleansing effect. Confession of sin means the judgment in our own hearts and minds of what we confess. And that means cleansing from its influence and deliverance from its power.

If we refuse to confess the wrong we have done to others, God may have to deal with us about it, and compel us to confess it. Unconfessed sin may be the cause of much sorrowful exercise of soul, as was the case with David, recorded in the Psalms. He said, when in great distress about unconfessed sin, "Day and night Thy hand (that is God's hand) was heavy upon me" (Psalm 32:4). This was how God spoke to him and made him feel his guilt, so that he might humble himself and confess his sin. After he did humble himself and confess his sin, he was able to say, "I acknowledged my sin to Thee (that is, to God), and my iniquity have I not hid. I said, I will confess my transgression to the Lord, and Thou forgavest the iniquity of my sin" (Psalm 32:5). No doubt God searched him when he was trying to conceal his sin. God does this to all His children, for He knows all their thoughts and ways. Nothing is hidden from Him. Hence we read, "O Lord, Thou hast searched me and known me. Thou knowest my downsitting and my uprising, Thou understandest my thought afar off. Thou compassest my path and my lying down, and art acquainted with all my ways." (Psalm 139:1-3).