"It may be said, without affecting excessive subtlety of definition,
that by imputation of Christ's righteousness, we only mean that
Christ's righteousness is so accounted to the sinner, as that he
receives thereupon the legal consequences to which it entitles."
"All are agreed that, when the Bible says, 'the iniquity of us all was
laid on Christ,' or that 'He bare our sins,' or 'was made sin for us,'
it is only our guilt and not our moral attribute of sinfulness which
was imputed. So it seems to me far more reasonable and scriptural to
suppose that, in the imputation of Christ's righteousness, it is not
the attribute of righteousness in Christ which is imputed, but that
which is the exact counterpart of guilt--the title to acquittal." ~
Systematic Theology in Lecture LIV (pg. 641 of the Zondervan edition)