2 The most important duty of the Church, and the one most peculiarly her own, is to defend and to propagate throughout the world the Kingdom of the Son of God, and to bring all men to salvation by communicating to them the divine benefits, so much so that her power and authority are chiefly exercised in this one work. Towards this end We are conscious of having devoted Our energies throughout Our difficult and anxious Pontificate even to the present day. And you too, Venerable Brethren, are wont constantly, yea daily, to give your chief thoughts and endeavours together with Ourselves to the self same task. But at the present moment all of us ought to make still further efforts, more especially on the occasion of the Holy Year, to disseminate far and wide the better knowledge and love of Jesus Christ by teaching, persuading, exhorting, if perchance our voice can be heard; and this, not so much to those who are ever ready to listen willingly to Christian teachings, but to those most unfortunate men who, whilst professing the Christian name, live strangers to the faith and love of Christ. For these we feel the profoundest pity: these above all would we urge to think seriously of their present life and what its consequences will be if they do not repent.
Source: Tametsi Futura Prospicientibus (Vatican.va)