Ad Gentes §10

¹⁰ The Church, sent by Christ to reveal and to communicate the love of God to all men and nations, is aware that there still remains a gigantic missionary task for her to accomplish. For the Gospel message has not yet, or hardly yet, been heard by two million human beings (and their number is increasing daily), who are formed into large and distinct groups by permanent cultural ties, by ancient religious traditions, and by firm bonds of social necessity. Some of these men are followers of one of the great religions, but others remain strangers to the very knowledge of God, while still others expressly deny His existence, and sometimes even attack it. The Church, in order to be able to offer all of them the mystery of salvation and the life brought by God, must implant herself into these groups for the same motive which led Christ to bind Himself, in virtue of His Incarnation, to certain social and cultural conditions of those human beings among whom He dwelt. ARTICLE 1: Christian Witness