Redemptoris Missio §7

⁷ The urgency of missionary activity derives from the radical newness of life brought by Christ and lived by his followers. This new life is a gift from God, and people are asked to accept and develop it, if they wish to realize the fullness of their vocation in conformity to Christ. The whole New Testament is a hymn to the new life of those who believe in Christ and live in his Church. Salvation in Christ, as witnessed to and proclaimed by the Church, is God's self-communication: "It is love which not only creates the good, but also grants participation in the very life of God: Father, Son and Holy Spirit. For he who loves desires to give himself." God offers mankind this newness of life. "Can one reject Christ and everything that he has brought about in the history of mankind? Of course one can. Man is free. He can say 'no' to God. He can say 'no' to Christ. But the fundamental question remains: Is it legitimate to do this? And what would make it legitimate?"