Overthrows pride

The mature moral result of Confession is its humiliation. If God commanded us to confess to Him alone, our sorrow would perhaps be as deep, and our purpose of amendment as sincere, but it would not be as humiliating as the truthful disclosure of our sins to a fellowman. We are so constituted by nature that the visible affects us more than the invisible. Very little humiliation would therefore accompany the secret telling of our sins, just as, indeed, very little shame and embarrassment accompany their commission before the veiled face of the unseen seen yet ever-present God. 

The fruitful confusion associated with Confession, which often prevents recourse to it, is an inestimable benefit. It overthrows our pride, the cause of all our sins; it deepens our humility, the foundation of all virtue, by making us share in Christ's unspeakable humiliations; it confounds us before one instead of millions. 

Furthermore, from another angle, Confession is especially beneficial. A thought expressed is a far more palpable reality than when it remains a mere mental existence. Words clarify the vagueness of ideas. They imprint print themselves upon the mind with a vividness wholly beyond the power of what is unformulated. Words can fill the heart with joy or crush it with sorrow, whereas thoughts not shaped in words, and therefore dormant, can wield no such influence.

John A. Kane. How to Make a Good Confession: A Pocket Guide to Reconciliation With God (Kindle Locations 362-369). Kindle Edition.