16 This intervention in the social question will bring you likewise to occupy yourselves with the lot of so many poor workingmen who too easily become the prey of de-Christianizing propaganda, with the mirage of economic advantages presented to them as a reward for their apostasy from God and from His Church. If you truly love the laborer (and you must love him because his conditions of life approach nearer to those of the Divine Master), you must assist him materially and religiously. Materially, bringing about in his favor the practice not only of commutative justice but also of social justice, that is, all those provisions which aim at relieving the condition of the proletarian; and then, religiously, giving him again the religious comforts without which he will struggle in a materialism that brutalizes him and degrades him.
Source: Firmissimam Constantiam (Vatican.va)