The Council itself, in the Dogmatic Constitution Lumen Gentium, said this: While Christ, 'holy, innocent and undefiled' (Heb 7:26) knew nothing of sin (cf. 2 Cor 5:21), but came only to expiate the sins of the people (cf. Heb 2:17)...the Church...clasping sinners to its bosom, at once holy and always in need of purification, follows constantly the path of penance and renewal. The Church, 'like a stranger in a foreign land, presses forward amid the persecutions of the world and the consolations of God', announcing the cross and death of the Lord until he comes (cf. 1 Cor 11:26).
Pope Benedict XVI, Apostolic Letter, Porta Fidei