Indifferentism, in the Roman Catholic faith, is the belief held by some that no one religion or philosophy is superior to another. The Catholic Church ascribes indifferentism to many atheistic, materialistic, pantheistic, and agnostic philosophies. There are three basic types of indifferentism described by Catholic apologetics: absolute, restricted, and liberal or latitudinarian indifferentism. Indifferentism was first explicitly identified and opposed by Pope Gregory XVI, in his encyclical Mirari vos.
Religious Indifferentism is to be distinguished from political indifferentism, which is applied to the policy of a state that treats all the religions within its borders as being on an equal footing before the law of the country. Indifferentism is not to be confounded with religious indifference. The former is primarily a theory disparaging the value of religion; the latter term designates the conduct of those who, whether they do or do not believe in the necessity and utility of religion, do in fact neglect to fulfill its duties.
Errors of modernism identified by beliefs that: every man is free to embrace and profess that religion which, guided by the light of reason, he shall consider true. (Papal Allocution, Maxima Quidem, 9 June 1862; Damnatio, Multiplices Inter, 10 June 1851).