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 ).
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.