Some religions may have modified the doctrine to follow from time to time so that it is appropriate. However, some religions are still adhering to the old model without modifications by era.
Some religious doctrine may be modified from time to time in order to be eligible. But some still cling to the old religion without modification of the period.
some religious doctrine may be modified over time to be appropriate. But some religion still adheres to the old style without having to modify according to age.