God made everything perfect until Satan decided to question his creation and use lies and trickery to convince hundreds of angel to follow him into destructions. We already know from the bible that there is no truth in the Devil and he is the master of lies.
You need to understand that the vile actions of the Devil and the curse that it put into our world were the reason why Christ had to die so that we can be redeemed. God is never going to forgive Satan for what he did, and eternal damnation is Satan only reward.
Because there is no redemption for Satan those who insist on following him will be told on the day of judgement as is written here in the book of Matthew 25: 41 Then shall he say also unto them on the left hand, Depart from me, ye cursed, into everlasting fire, prepared for the devil and his angels:
The Creator is describing the Devil and his followers her in the book of John 8:44 Ye are of your father the devil, and the lusts of your father ye will do. He was a murderer from the beginning, and abode not in the truth, because there is no truth in him. When he speaketh a lie, he speaketh of his own: for he is a liar and the father of it.
Of course, the devil believes God exists; in fact, Satan has no doubts about it. But he doesn’t trust God; instead, he set himself up in opposition to God. But he also knows that one day the final battle will be fought and that God alone will be victorious. That is why the Bible says in, James 2:19 Thou believest that there is one God; thou doest well: the devils also believe, and tremble.