Originally posted by Grand_Moff_Gav
He set out to overthrow God...he failed. He now gets back at God by picking on beings far lesser than him in power...he even fails in that.
Now you're moving the goal post. You said he is a failure, while possibly true in the big picture, he certainly doesn't always fail. The Adam & Eve story being one example.
If souls are in hell, then ultimately it is because they were weak and fell to some temptation ie "The Devil". Seems he doesn't always fail in that aspect either.