CIC 602 Consequently, St. Peter can formulate the apostolic faith in the divine plan of salvation in this way: “You were ransomed from the futile ways inherited from your fathers. .. with the precious blood of Christ, like that of a lamb without blemish or spot. He was destined before the foundation of the world but was made manifest at the end of the times for your sake.”1 Man’s sins, following on original sin, are punishable by death.2 By sending his own Son in the form of a slave, in the form of a fallen humanity, on account of sin, God “made him to be sin who knew no sin, so that in him we might become the righteousness of God.”3

1 I Pt 1:18-20.
2 Cf. Rom 5:12; I Cor 15:56.
3 2 Cor 5:21; cf. Phil 2:7; Rom 8:3.