God, in Christ, has declared us not-guilty; this is the work of Justification by which we have been declared righteous for Christ’s sake. Having received the imputed righteousness of Jesus Christ, by which we are declared just before God. In this way the verdict declared from Mt. Calvary, for all sinners, is “not guilty” because Christ has attained and accomplished what He has accomplished on the Cross–this is the meaning of Romans 5:18 where all are called justified. The formal theological term here would be “Objective Justification”. I personally benefit of this through hearing of the Gospel which the Holy Spirit uses to work and create faith in me, by which I am justified by faith (Subjective Justification) and thus the objective work of Christ becomes mine personally. Thus I hear the declared word of God in the Gospel that I am forgiven–my guilt is wiped away, through the full pardon of God in Christ, by which I am now declared justified for Christ’s sake.
In this way also, when I am brought to the precious waters of Holy Baptism and I am washed clean and made new (John 3:5, Titus 3:5 etc) I can say that I am washed clean of the Original Guilt which I inherited from Adam. For in Adam I am guilty and dead, I have received Adam’s Original Guilt, by which I enter the world not only capable of sinning, but already a dead sinner. So the Old Man (Adam) having been nailed to the cross, and declared justified by the Gospel, and washed clean in Holy Baptism I am, indeed, what God declares me to be in Christ: holy and blameless and indeed righteous. Though it is not my righteousness, but Christ’s. It is not my holiness, but God’s holiness. It is not that I am blameless in my works, it is that Christ is blameless and I am now clothed with Him (Galatians 3:27).
This is the important half of the Simul, that we are simul iustus et peccator. We are both saints and sinners. We are saints, because we bear the New Man which is holy and perfect–the new man of Jesus Christ, who is the New and Second Adam. But lest we forget: We are also sinners, for the Old Man, the old Adam, still dwells in our flesh. This is why St. Paul himself writes that it is as though there is a law of sin and death at work in his bodily members, so that the good he wants to do he fails to do, and the evil he doesn’t want to do he still does. Because while the mind knows what is right and what is wrong, we still fail. This is the Old Man.
This is why Scripture calls us to repentance. Not as though the perfect work of Christ isn’t perfect, but because the old man needs to be continually put to death, we need to subject our bodily members to God. We need our minds transformed, rather than conformed to the pattern of this world; to walk in the will and way of God as God works in us to keep working us into the image of Christ. Which is also why the Apostle says “Work out your salvation with fear and trembling”, not because salvation is about works, but because the ongoing work of sanctification is ongoing, we need to always be at the receiving end of grace. I can’t hear a sermon once, and then go live however I want. I need to hear the Gospel, always. I need to repent, all the time. I need the Gospel preached, to strengthen faith so that I am ever clinging to the Cross of Jesus Christ; and I need the Law to mortify my flesh and remind me that I am, without Christ, dead and a wretch.
So it is absolutely true that we are guiltless in Christ, being justified freely by God’s grace, received through faith. This is a true and precious declaration of the Holy Gospel.
It is also absolutely true that I am, in my flesh, full of guilt, and thus I must kneel before God, praying and trusting only in mercy, that I might be mortified in my flesh, penitent in spirit, and always brought to Mt. Calvary where Christ our Lord was crucified for us. And there cry Holy Holy Holy, now today, as it will be forever and ever.