Many Satanist know full-well that he is not a metaphor.
Here's how they see things:
They see Satan as an angel of light and believe he is alive and well.
They see Satan as a very active spirit that wants to liberate them from the chains of God's rules. They see the Tree of Knowledge of Good and Evil as a portal to Enlightenment that God wanted to deprive them of. They see sex as a very good thing, particularly when unencumbered by God's stifling demands that it be limited to marriage and only between adult members of the opposite sex.
Satanists believe that God wants to imprison people--to make slaves of them. They believe that Satan is here to set them free.
As Sun Tzu said a very long time ago" "Know your enemy. If you don't, you are going to lose the battle you are fighting."
Most Christians and Jews have no idea what Satanists believe. We had better get with the program and stop thinking inside the box as Michael Brown does in this article. As an aside, I have been watching and reading Michael Brown for years and think he does a great job. But occasionally, he misses the mark.
Good summation.