Haven't finished the episode yet, but fuck, the Seal of Solomon seals demons and makes them serve god again, that's the whole point of it, why would that be satanic? The story is that Solomon was given the signet ring by an angel to make demons build the temple for him.
Unrelated, I'm not hearing any reasons why I should support God in this one, Satan seems to have this one in the bag and neither side gives me free will (what with having to pray or demonic mind control), and at least Satan is less preachy about it
Edit: Vav/Waw is the 6th letter in Hebrew, but since the number of the beast isn't 6,6,6, but 666, it'd actually be TRSW (Taw, Resh, Samekh, Waw, because numerical values go up to 400 so there isn't a 600)