Missionaries spread the good news of the Gospel. They do not work to convert people per se.
Very misunderstood.
[16] And the eleven disciples went into Galilee, unto the mountain where Jesus had appointed them. [17] And seeing him they adored: but some doubted. [18] And Jesus coming, spoke to them, saying: All power is given to me in heaven and in earth. [19] Going therefore, teach ye all nations; baptizing them in the name of the Father, and of the Son, and of the Holy Ghost. [20] Teaching them to observe all things whatsoever I have commanded you: and behold I am with you all days, even to the consummation of the world.
Matthew; Chapter 28
[18] All power: See here the warrant and commission of the apostles and their successors, the bishops and pastors of Christ’s church. He received from his Father all power in heaven and in earth: and in virtue of this power, he sends them (even as his Father sent him, St. John 20. 21) to teach and disciple, not one, but all nations; and instruct them in all truths: and that he may assist them effectually in the execution of this commission, he promises to be with them, not for three or four hundred years only, but all days, even to the consummation of the world. How then could the Catholic Church ever go astray; having always with her pastors, as is here promised, Christ himself, who is the way, the truth, and the life. St. John 14.
God is the one who converts man’s heart.