118 For, according to Christian teaching, man, endowed with a social nature, is placed on this earth so that by leading a life in society and under an authority ordained of God he may fully cultivate and develop all his faculties unto the praise and glory of his Creator; and that by faithfully fulfilling the duties of his craft or other calling he may obtain for himself temporal and at the same time eternal happiness. Socialism, on the other hand, wholly ignoring and indifferent to this sublime end of both man and society, affirms that human association has been instituted for the sake of material advantage alone.
Source: Quadragesimo Anno (Vatican.va)