Always enjoyed the lore behind Forbidden Mountain. Maleficent should hook up with Lucifer more often.
Chernabog is a anthropomorphism of winter from slavic mythology
This is why the song he appears in fantasia is called "right of spring" and why at the end it shows a peaceful meadow during spring.
Also Maleficent is a faerie and has no association with satan or chernabog for that matter.