Satan was defeated in the garden. He knew it then. It was declared so by God Himself.

"And the LORD God said unto the serpent, Because thou hast done this, thou [art] cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:
And I will put enmity between thee and the woman, and between thy seed and her seed; it shall break thy head, and thou shalt bruise his heel" Gen3:14.15

The mission then going forward, as it remains to this very moment in time and for a very relatively short while more, is how many of us he will be able to *deceive* into going down with him.

'Be careful who you follow'