Sanatana Dharma – open to updating
In Santana Dharma (eternal religion), we have two scriptures. Sanatana Dharma is the only courageous dharma(religion), to have two kinds of scriptures. In all other religions on the planet earth, they have only one scripture, one book, ultimate! That is all. There are many religions, which say their holy book can't be updated. Even software can be updated! There are many religions that say their book can never be updated. But Sanatana Dharma is the only courageous religion, which says their book can be updated.
Shruti and Smruti
They divided into two portions; śruti (veda) and smṛti (sacred traditional books). Smṛti means the ultimate laws about enlightenment; Ātman, the concept or realization, about the universe. Smṛti means the social laws, day-to-day rules and regulations. The courageous people declared smṛti can be changed. Time to time enlightened masters can create new smṛti, because we know that no morality can be morality forever. No law can be law forever. Because, morality and law are based on the situation!
For example, if the deer population becomes too much, you are allowed to hunt. Same way, once upon a time in Bharat, cows' population was too much. That is why they started giving cows in the sacrifices. Once the cow population became too low, they started to worship the cows.
The rules are created to maintain equilibrium in the society; to maintain harmony in the society. When we all live together, we need a few basic understandings to live happily. For example, you will not try to kill me so that I will not kill you. That is all. You will not try to kill me so that I will not try to kill you. We both can live happily without fear. Like this, a few basic understandings are assumed or come into being. Slowly, by and by, they become rules. They become morality.
The problem is, as long as you understand the root of morality, you neither behave immorally nor you get disturbed by this morality. Once you don't understand the rule, once it becomes just a spoon feeding, a sort of forced rule, then not only you try to escape from that rule, but also you create a deep guilt in you. When it is a forced rule, you always try to go beyond it; for example, you always over speed when you don't see the cop!