33 St. Justinus, Minucius Felix, Aristides, the consul Acilius Glaber, the patrician Flavius Clemens, St. Tarsicius and countless holy martyrs of both sexes, who strengthened and enriched the growth of the Church by their labors and the shedding of their blood, can in a certain sense be called the advance guard and forerunners of Catholic Action. Here We wish to cite the striking observation of the author of the letter to Diognetus, which even today has a message for us: "Christians dwell in their native countries as though aliens; . . . every foreign land is their home and the land of their birth is foreign soil."
Source: Evangelii Praecones (Vatican.va)