Enoch is mentioned in Genesis as being assumed into heaven and the Letter of Jude mentions Enoch. According to some sources, at one time, Enoch was in the canon of scripture. Reliability… I don’t know, it has good theology in it and as I said Jude mentions Enoch.
According to Genesis and Enoch the world is destroyed by flood because the Sons of God, (Angels presumedly) have had sexual relations with mortal women and gave birth to the Nephilim. This is considered to be the sin that causes Satan and his cohorts to be cast out of Heaven. Note that this occurs later in Genesis, after the fall of man. So, that calls into question, who was the snake? How could he be Satan if he hasn’t been cast out of Heaven yet? The answer is, don’t take this literally, the fall of man shows that man thumbed his nose at God and thus death is introduced into the world.
As a side bar, my favorite quote from Enoch is when God gives to the Archangel Gabriel the order to advance against Satan, (Semjaza, the angel who is considered a member of the Angelic Choir of Powers and not an Archangel).
~And to Gabriel said the Lord: “Proceed against the bastards and reprobates…~” :eek: