But there lies the issue. Who decides what is light and what is dark. In most religions, this is one of the main of the reasons why they split into numerous denominations and denominations split into various schisms.
A good example of this is the book of Leviticus that makes an appearance in the Hebrew Bible and the Jewish Torah. This book lists an extensive range of "offences" and their corresponding penalties, many of which was death. Some of these are typically held as norms by almost all of the world (like murder, assault, incest, purgery, stealing and dishonest business practices). Most would be viewed as really extreme in a civilised society (like letting your hair become unkempt, eating fat, trimming your beard, mixing fabrics in clothing and planting different seeds in the same field). A few are still the cause of differing opinion between / within denominations today (like homosexuality, getting tattoos and touching seafood that has no fins or scales ).
The point is that when Leviticus was written, all the rules listed in it was for the purpose of "staying in the light". Now, most of these rules are typically viewed as weird or evil.