Redemptoris Missio §77

⁷⁷ Since they are members of the Church by virtue of their Baptism, all Christians share responsibility for missionary activity. "Missionary cooperation" is the expression used to describe the sharing by communities and individual Christians in this right and duty. Missionary cooperation is rooted and lived, above all, in personal union with Christ. Only if we are united to him as the branches to the vine (cf. Jn 15:5) can we produce good fruit. Through holiness of life every Christian can become a fruitful part of the Church's mission. The Second Vatican Council invited all "to a profound interior renewal, so that having a lively awareness of their personal responsibility for the spreading of the Gospel, they may play their part in missionary work among the nations." Sharing in the universal mission therefore is not limited to certain specific activities, but is the sign of maturity in faith and of a Christian life that bears fruit. In this way, individual believers extend the reach of their charity and show concern for those both far and near. They pray for the missions and missionary vocations. They help missionaries and follow their work with interest. And when missionaries return, they welcome them with the same joy with which the first Christian communities heard from the apostles the marvelous things which God had wrought through their preaching (cf. Acts 14:27).