Verse 9. "If we confess our sins" - If, from a deep sense of our guilt, impurity, and helplessness, we humble ourselves before God, acknowledging our iniquity, his holiness, and our own utter helplessness, and implore mercy for his sake who has died for us; he is faithful, because to such he has promised mercy, Psa. xxxii. 5; Prov. xxviii. 13; and just, for Christ has died for us, and thus made an atonement to the Divine justice; so that God can now be just, and yet the justifier of him who believeth in Jesus.
"And to cleanse us from all unrighteousness." - Not only to forgive the sin, but to purify the heart.
1. Sin exists in the soul after two modes or forms: (1.) In guilt, which requires forgiveness or pardon. (2.) In pollution, which requires cleansing.
2. Guilt, to be forgiven, must be confessed; and pollution, to be cleansed, must be also confessed. In order to find mercy, a man must know and feel himself to be a sinner, that he may fervently apply to God for pardon; in order to get a clean heart, a man must know and feel its depravity, acknowledge and deplore it before God, in order to be fully sanctified.
3. Few are pardoned, because they do not feel and confess their sins; and few are sanctified or cleansed from all sin, because they do not feel and confess their own sore, and the plague of their hearts.
4. As the blood of Jesus Christ, the merit of his passion and death, applied by faith, purges the conscience from all dead works, so the same cleanses the heart from all unrighteousness.
5. As all unrighteousness is sin, so he that is cleansed from all unrighteousness is cleansed from all sin. To attempt to evade this, and plead for the continuance of sin in the heart through life, is ungrateful, wicked, and even blasphemous; for as he who says he has not sinned, ver. 10, makes God a liar, who has declared the contrary through every part of his revelation; so he that says the blood of Christ either cannot or will not cleanse us from all sin in this life, gives also the lie to his Maker, who has declared the contrary, and thus shows that the word - the doctrine of God is not in him.
Reader, it is the birthright of every child of God to be cleansed from all sin, to keep himself unspotted from the world, and so to live as never more to offend his Maker. All things are possible to him that believeth; because all things are possible to the infinitely meritorious blood and energetic Spirit of the Lord Jesus. See the notes on the parallel passages in the margin; and particularly in St. John's gospel, John 1.