Indifferentism is the belief held by some that no one religion or philosophy is superior to another.
Political indifferentism relates 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. Meanwhile, religious indifferentism is the belief that all religions are equally valid. However, in Catholic usage religious indifference is a term for the behavior of "deny[ing] that it is the duty of man to worship God by believing and practicing the one true religion".
Source: Wikipedia
2. Man may, in the observance of any religion whatever, find the way of eternal salvation, and arrive at eternal salvation. (Papal Encyclical, Qui Pluribus, 9 November 1846).
3. Moreover, it is false that the civil liberty of every form of worship, and the full power, given to all, of overtly and publicly manifesting any opinions whatsoever and thoughts, conduce more easily to corrupt the morals and minds of the people, and to propagate the pest of indifferentism. (Papal Allocution, Nunquam Fore, 15 December 1856).