It's not so much them being a theocracy IMHO. It's that they believe they have a religious duty to destroy the state of Israel.
Put those Israeli shoes on. There's a state armed with ballistic missiles in easy range of you, they have the facilities necessary to enrich weapons grade Uranium, recently acquired more advanced centrifuges, they have the uranium already enriched far beyond what's necessary for civilian use, they have far more of it than they credibly need for such civilian use, and they believe god has ordered them to destroy you.
Put those Israeli shoes on. There's a state armed with ballistic missiles in easy range of you, they have the facilities necessary to enrich weapons grade Uranium, recently acquired more advanced centrifuges, they have the uranium already enriched far beyond what's necessary for civilian use, they have far more of it than they credibly need for such civilian use, and they believe god has ordered them to destroy you.
How well would you sleep at night?