Charles Hodge: Justification is objective and forensic because it is grounded in extrinsic, imputed righteousness

The nature of justification is determined by its ground. This indeed is an anticipation of another part of the subject, but it is in point here. If the Bible teaches that the ground of justification, the reason why God remits to us the penalty of the law and accepts us as righteous in his sight, is something out of ourselves, something done for us, and not what we do or experience, then it of necessity follows that justification is not subjective. It does not consist in the infusion of righteousness, or in making the person justified personally holy. If the “formal cause” of our justification be our goodness; then we are justified for what we are. The Bible, however, teaches that no man living can be justified for what he is. He is condemned for what he is and for what he does. He is justified for what Christ has done for him. (Charles Hodge, Systematic Theology, vol. III)