Every Christian is called to be a missionary through prayer, working in collaboration with the Holy Spirit, who gives prayer efficacy, Pope Francis said in a video message to the Pontifical Mission Societies Monday.

“Prayer is the first ‘missionary work’ — the first! — that every Christian can and must do, and it is also the most effective, even if this cannot be measured,” the pope said May 28. “In fact, the principal agent of evangelization is the Holy Spirit, and we are called to collaborate with Him.”

Announcing the Gospel is a “common task,” Francis said, encouraging Catholics to support areas where the Church is new. Through support for the missionary societies “the Church continues to open itself to everyone and to joyfully proclaim the Good News of Jesus Christ, Savior of the world,” he said.

The Pontifical Mission Societies is an international secretariat overseeing Catholic missionary societies under the jurisdiction of the pope. It helps support churches, especially in areas where Christianity is new or not well-off. The group is meeting in Rome for a general assembly through June 2.

Pope Francis said these societies distribute aid, in the name of the pope, to churches around the world which need monetary assistance for priests and catechists, seminaries, or pastoral and evangelical work.

The societies financially support missionaries, he said, but especially, they support evangelization “with prayer, so that the Holy Spirit may be present,” because it is the Spirit “who advances evangelization.”

“Why are the Pontifical Mission Societies important?” Pope Francis asked. “Above all, they are important because we must pray for missionaries, for the evangelizing action of the Church.”

He noted that the societies were founded in the 19th century for “praying and acting concretely to support evangelization.”

Pope Piux XI recognized the societies as pontifical, he continued, in order to underline that the mission of the Church is very close to the heart of the pope: “And so it is still!”

“The Pontifical Mission Societies continue today this important service started almost 200 years ago,” he said. “From the earliest times, mutual support among the local Churches, committed to proclaiming and bearing witness to the Gospel, has been a sign of the universal Church.”