The question then might be, "If the Devil Should Die Can God Credibly Make Another?"
It's a tough question, especially if we treat the Devil of the OT the way Christianity does-- as a fallen angel who became an arch-enemy of god.
As the teaching goes, once Adam and Eve partook of the forbidden fruit, they were sinners. Imperfect. And they would pass this imperfect state on to their offspring. Humanity had fallen. Being imperfect meant that they were, well... genetically engineered to sin, I guess you could say. No serpent or Devil required, at this point. Nonetheless, not only does god let Satan live, he gives him a part in the re-establishment of god's kingdom and the redemption of mankind. The serpent would "wound" the Son of Man on the heel at some future time. God had now committed himself; Satan had to play this part, or god would be a false prophet.
Later, when more angels fell from grace and introduced hybrid man-monsters to the world, god decided that this was enough! He had to take action, and so he did... by condemning
humanity to a near-complete genocide. What this accomplished is difficult to determine-- man's sinful nature had not been changed, and it's no surprise that shortly after Noah and his family stepped from the ark, they were being sinful little bastards all over again. God could've killed those fallen angels, but didn't. And there seems no reason for him not to have. Not only did they not figure in his future plans for redeeming mankind, but they would now spend the coming centuries mucking around and leading people away from god. By all accounts the people who were misled by those demons --with their get-out-of-Gehenna-free cards-- would suffer for doing so. Sorry, suckers, guess you should learn to distinguish between
magic and
miracles.
Satan takes advantage of this massive loophole. He talks god into allowing Job to suffer unspeakable wickedness, then smirks as god scolds Job for being understandably annoyed. God also scolds the false friends that Satan had sent to torment Job, leaving their fate in Job's hands
[1]. I suppose that god trashed-talked the Devil any time he saw him after that, but remember... he still needed Satan around. Otherwise, who could he turn to when he needed someone to tempt Jesus and then arrange for Christ's painful torture and murder?
Anyway... once Adam and Eve sinned and degraded their DNA, the Devil was superfluous... except that god included him in his future plans. Had Satan died at any time in the interim, god pretty much
had to make another, if only to keep up appearances. We can't have Satan making god look bad, can we?
*raucous laughter from the crowd*