The state (the U.S. Constitution) has not the right to leave every man free to profess and embrace whatever religion he may desire.
Pope Pius IXIf anyone says that it is possible that at some time, given the advancement of knowledge, a sense may be assigned to the dogmas propounded by the Church which is different from that which the Church has understood and understands: let him be anathema.
Pope Pius IXNow you know well that the most deadly foes of the Catholic religion have always waged a fierce war, but without success, against this Chair [of St. Peter]; they are by no means ignorant of the fact that religion itself can never totter and fall while this Chair remains intact, the Chair which rests on the rock which the proud gates of hell cannot overthrow and in which there is the whole and perfect solidity of the Christian religion.
Pope Pius IXIt is error to believe that Every man is free to embrace and profess that religion which, guided by the light of reason, he shall consider true.
Pope Pius IXThe civil liberty of every mode of worship, and full power given to all of openly and publicly manifesting their opinions and their ideas conduce more easily to corrupt the morals and minds of the people... The Roman Pontiff cannot and ought not to reconcile himself or agree with, progress, liberalism and modern civilization.
Pope Pius IX