Demons aren’t people, they don’t have access to saving grace. They made their choice long ago and are stuck with it. However even the vilest human can receive forgiveness and eternal life just by asking for it (and really meaning it, of course). Osama bin Laden can be saved if he wants it, but Satan and his demons can’t.
I’m glad that your earlier post wasn’t “at face value” (because it did not make any point about what is required to receive redemption clear but seemed as if it could indicate that mere intellectual belief was sufficient ... thus my comment).