1. In the first place it is not "the righteousness of Christ" which is imputed to the saint, but simply "righteousness" or "justification", two translations of the same Greek word. The convicted felon who has done his time comes out of prison "justified" or "righteous", and it is a legal offence to speak of him any longer as a criminal or convict. He has "paid" for his crime, he is "justified", and re-enters society as a free man. But that does not mean that he is also credited with all the virtues of his country's most famous citizen! No man can have the virtues or sins of another man imputed to him: nor will God impute to any man the perfect righteousness of Christ. He has the name which is above every name.
"The righteousness of Christ" is a phrase which means the perfect character of Christ, and the theory, which holds that this is imputed to the sinner, is responsible for the grave doctrinal error that, when the Christian stands before the Judgement of Christ, God will not see him but only Christ, and will therefore count him as perfect. This is of course completely unscriptural, and makes nonsense of the race for the crown of which Paul speaks in 1 Cor. 9,25, and of the danger of losing that crown of which the Lord speaks in Rev. 3,11.
It is not "the righteousness of Christ" which is imputed to the sinner, but His death. Christ paid our penalty by His death on Calvary, and upon certain terms God accepts this as our death. The terms are, that we agree that the wages of sin is death and that God ought justly to kill us; that we repent of our own sin, which act gives a guarantee for the future; and that we gratefully accept the sacrifice of Jesus on our behalf which kills "the old man" and starts us on our new life with a clean heart. So long as we hold this faith firm unto the end there is no question of our coming into judgement of life or death. Eternal life with God is ours, unless we deliberately throw it away in hatred and contempt and thus commit spiritual suicide.19 But Paul desired that we should not merely be saved, but be saved with glory,20 and it is the deeds done in our body, not in Christ's, which will bring us shame or glory as the case may be.21
2. In the second place there is an entire misunderstanding of the meaning of the word "guilt". The Concise Oxford