Religious reform

[1] Mostly the deviation from the assumed true faith which gives reason for a religious reform crept in over a longer period of time, sometimes over centuries.

A typical example for deviations from an assumed true faith are social changes within society which lead a loss purpose for ethical prescriptions, so they have to be replaced by other ethical prescriptions in order to protect the underlying, unchanged value for the future.

[2] The eternally continuing change of society and the progress of human knowledge are the reasons why a "final" reform of religious teachings is not possible.

An example is the attempt of the Roman emperor Julian the Apostate to restore paganism as state religion.

The adherents of reforms to adjust to the spirit of the time in the first place without respect for an assumed true faith are called modernists, their ideology is modernism.