Divini Redemptoris §16

¹⁶ If we would explain the blind acceptance of Communism by so many thousands of workmen, we must remember that the way had been already prepared for it by the religious and moral destitution in which wage-earners had been left by liberal economics. Even on Sundays and holy days, labor-shifts were given no time to attend to their essential religious duties. No one thought of building churches within convenient distance of factories, nor of facilitating the work of the priest. On the contrary, laicism was actively and persistently promoted, with the result that we are now reaping the fruits of the errors so often denounced by Our Predecessors and by Ourselves. It can surprise no one that the Communistic fallacy should be spreading in a world already to a large extent de-Christianized.