Catholicism and Socialism Are Incompatible

“If Socialism, like all errors, contains some truth (which, moreover, the Supreme Pontiffs have never denied), it is based nevertheless on a theory of human society peculiar to itself and irreconcilable with true Christianity.  Religious socialism, Christian socialism, are contradictory terms; no one can be at the same time a good Catholic and a true socialist.”
(Pope Pius XI, Quadragesimo Anno, para. 121)