81 To hasten the advent of that "peace of Christ in the kingdom of Christ" so ardently desired by all, We place the vast campaign of the Church against world Communism under the standard of St. Joseph, her mighty Protector. He belongs to the working-class, and he bore the burdens of poverty for himself and the Holy Family, whose tender and vigilant head he was. To him was entrusted the Divine Child when Herod loosed his assassins against Him. In a life of faithful performance of everyday duties, he left an example for all those who must gain their bread by the toil of their hands. He won for himself the title of "The Just," serving thus as a living model of that Christian justice which should reign in social life.
Source: Divini Redemptoris (Vatican.va)