The present study is made up of three parts. The first one, entitled the notion of sin by Stanislas Lyonnet, starts from the observation that redemption is essentially the destruction of sin. For this reason the treatise on redemption in the New Testament is preceded by an inquiry into the notion of sin, as it derives from the Old Testament, especially from the account of Genesis 3. The second part, also from Stanislas Lyonnet, is devoted to the terminology of redemption in the N.T. The third part, by Leopold Sabourin, is about sacrifice and redemption in the history of St. Paul's formula Christ made sin (2 Cor 5,21). The author examines the most representative testimonies of the ancient and Medieval Greek and Latin writers, and exposes his interpretation of 2 Cor 5, 21, in which the notion of sacrifice for sin appears as a key concept in this formulation.