I understand that Satan’s choice to turn away from God is irrevocable, but I don’t understand how he could have made that choice in the first place when he has perfect intellect. Couldn’t his mind tell him that he would lose against God? Couldn’t it tell him that he’s best off with God?
Yes, but the choice for hell primarily is a matter of free will. Satan’s choice for hell demonstrates that even those with perfect intellect can freely choose to reject God, perhaps merely because they can.