“If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.”
King James Version (KJV)
1:9 But if with a penitent and believing heart, we confess our sins, he is faithful - Because he had promised this blessing, by the unanimous voice of all his prophets. Just - Surely then he will punish: no; for this very reason he will pardon. This may seem strange; but upon the evangelical principle of atonement and redemption, it is undoubtedly true; because, when the debt is paid, or the purchase made, it is the part of equity to cancel the bond, and consign over the purchased possession. Both to forgive us our sins - To take away all the guilt of them. And to cleanse us from all unrighteousness - To purify our souls from every kind and every degree of it.
1Jo 1:9 If we confess our sins. Instead of affirming that we are sinless we should confess our sins. He is faithful and just. If we confess our sins the Lord will be "faithful" to his promise of mercy, and "just" in requiring us to have the atonement of Christ, "to forgive us our sins".