Fr. James Altman explains why Pope Saint Pius X said “Liberal Catholics are wolves in sheep’s clothing.”
“Let priests take care not to accept from the liberal any ideas which, under the mask of good, pretend to reconcile justice with iniquity. Liberal Catholics are wolves in sheep’s clothing. The priest must unveil to the people their perfidious plot, their iniquitous design. You will be called Papist, clerical, retrograde, intolerant, but pay no heed to the derision and mockery of the wicked. Have courage; you must never yield, nor is there any need to yield. You must go into the attack whole-heartedly, not in secret but in public, not behind barred doors, but in the open, in the view of all.” -Pope St. Pius X