Forgiveness comes through grace, without any work, merit, or worthiness of ours preceding, present, or following...

We believe, teach, and confess what our righteousness before God is this:  God forgives our sins out of pure grace, without any work, merit, or worthiness of ours preceding, present, or following.  He presents and credits to us the righteousness of Christ's obedience.  Because of this righteousness, we are received into grace by God and regarded as righteous.

We believe, teach, and confess that faith alone is the means and instrument through which we lay hold of Christ.  So in Christ we lay hold of that righteousness that benefits us before God, for whose sake this faith is credited to us for righteousness.

We believe, teach and confess that this faith is not a bare knowledge of Christ' history, but it is God's gift.  By this gift we come to the right knowledge of Christ as our Redeemer in the Word of the Gospel. And we trust in Him that for the sake of His obedience alone we have--by grace--the forgiveness of sins and are regarded as holy and righteous before God the Father and are eternally saved.
~BOC, FE, III, 4-6

The Holy Spirit bestows, increases, and strengthens faith as He makes us holy as we abide in faith...

But the Holy Spirit carries on His work without ceasing to the Last Day.  For that purpose He has appointed a congregation upon earth by which He speaks and does everything.  For He has not yet brought together all His Christian Church or granted all forgiveness.  Therefore, we believe in Him who daily brings us into the fellowship of this Christian Church through the Word. Through the same Word and the forgiveness of sins He bestows, increases, and strengthens faith.  So when He has done it all, and we abide in this and die to the world and to all evil, He may finally make us perfectly and forever holy.  Even now we expect this in faith through the Word.
~BOC, LC, II, 61-62

Holy Spirit begins and daily increases holiness...

You see, all this is the Holy Spirit's office and work.  He begins and daily increases holiness upon earth through these two things:  the Christian Church and the forgiveness of sin.  But in our death He will accomplish it altogether in an instant and will forever preserve us therein by the last two parts [of the Creed].
~BOC, LC, II, 59

The gift of the Holy Spirit bring a daily cleansing and forgiveness...

Paul testifies that he wars with the law in his members not by his own powers, but by the gift of the Holy Spirit that follows the forgiveness of sins. This gift daily cleanses and sweeps out the remaining sins and works to make a person truly pure and holy.
~BOC, SA, III (III), 40