Ghost Rider has had a few iterations in the Marvel universe. The writers actually debated about bringing him back because he's insanely overpowered. The only real weakness he has is the human to which the entity that is the "Ghost Rider" is attached. Reminds me a bit of some Japanese anime that I watch, where an other worldly entity becomes one with a human host and grant them power to right wrongs and such. The entity that give the ghost rider his power is somewhat of an elemental rather than a true demon, that's why Satan doesn't have full control of him. It's a little like the character Spawn, if you're familiar with that one.
"L'essentiel est invisible pour les yeux."
What is essential is invisible to the eyes.
The Foxes Secret from The Little Prince by Antoine de Saint Exupéry