The variety and flexibility of Thomas’s terminology regarding Christ’s passion and sin is remarkable. In ST III, 49, 1, he asks whether Christ’s passion liberates from sin (liberati a peccato). Christ’s death brings freedom.
Then he shifts gears. Objection 2 says that “Christ’s Passion could not cleanse (mundare) us from sin.” In objection 4, he writes of “forgiveness” (remissio). At the end of the Respondeo, he concludes that Christ’s sufferings have divine power to “expel” sins (expellendum peccatum).
The terminological disconnect between the objection and response indicates that Thomas viewed these terms as virtually interchangeable. To an objection about “liberation” from sin, Thomas responds that Christ’s passion “expels” sin. To an objection about “cleansing,” Thomas responds with an argument about remissio. Objection 4 speaks of forgiveness, but the reply introduces a new concept, deletionem propriorum peccatorum.
Where Protestant theology generally distinguishes between forgiveness of the guilt of sin and liberation from the power of sin, Thomas smudges: Liberation is forgiveness is cleansing is expulsion is deletion. To be forgiven is, for Thomas, to be freed.