Humans were introduced to Hasatan in the Garden of Eden. Hasatan means "adversary". To be an adversary of the Creator, one opposes, ignores or resists the instructions of the Creator and is considered an enemy of the Creator. The test given to humanity was very simple and straight forward; Adam and Eve were not to touch or eat from one specific tree. Hasatan tempted humanity to follow their natural desires. The choice was either to listen and obey the Creator or listen to that other "voice'. The consequence for disobeying the instruction would be that every human would die a physical death with their soul being preserved until all humanity is judged to see if they served and followed the rules/instructions/statutes/mitzvots of the Creator. Those that have served and were obedient to the Creator, listend to the Prophets and acknowledged the testimony of the Son of Man, will be invited back to enjoy the New Earth, or in other words, the new Garden of Eden...Paradise without all the stuff.
The Creator expected each generation to pass down (oral tradtion) to the next generation His rules and expectations. When a generation fails to do so they in essence have become the other "voice". Humans are a conduit of information and nothing more than the sum total of their thoughts. It is easy to test whether parents have passed on to their children the Law Code of the Creator or something else.
Throughout our lives we will be mentally battling distractions, omissions, deceptions and outright lies. The Law Code is designed to help us navigate through the confusion given the reality that this is our first time living life in all of its stages. We are to humble ourselves and be guided by the Law Code and the Spirit of Truth.
There is nothing more evil than a parent being in possession of the Bible and never teaching their children who the Creator is and what He expects of them based on His Law Code.