Part of it is religious retardation but that doesn't explain why military leaders make these decisions. The answer is twofold
>1. Pressure from below to continuously attack Israel
Their citizens get whipped up into a frenzy over Israeli crimes and the leaders have to respond or be seen as weak if they don't, depending on the country. For "neutral" muslim countries like Egypt, Saudi Arabia, etc. that means strongly worded condemnations. For Iran (and many other muslim countries that were formerly aligned directly against Israel) that meant invasions and scud missile attacks
>2. Limiting the aura of Israeli inevitability
Israeli strategy in the middle east is to do incredibly provocative shit and then dare anyone to respond. Then if they respond to claim the victim and attack with overwhelming force. If they don't respond and kick the issue up to useless international bodies like the UN (with a US security council veto always in Israel's corner) then Israel gets away with it and can start preparing for the next escalation on the path to creating greater israel. In 1948 none of the Arab militaries were capable of defeating Israel, even Jordan, but they felt compelled to attack because not attacking would mean Israel got away with the expulsion of Palestinians from half of the territory scot free. Something similar is happening now. Even if Iran doesn't feel like they're ready it's probably a "now or never" scenario, where if they wait too long and let Israel repeatedly punch them in the face without response it will be too late to do it 5 years from now.
tl;dr - combination of pissed off fundamentalist muslims on the ground demanding action and a need to retaliate lest Israel get the impression that they have zero resistance and can do whatever they want