Why is Israel a republic?

Answer 1

As opposed to what? Monarchy? Communism? Dictatorship? Military Junta?

Israel was a state formed by secular Zionists who modeled the State of Israel after successful Western States. They promoted the values of equality before the law and proportional representation. It was also a way to avoid the religious qualms about a monarchy as the only divinely sanctioned monarchy in Jewish tradition is the Messianic Line.

As for communism, Israel was never Soviet aligned (though it came close). The Kibbutzim were socialist institutions, but they never held enough power to cow the right-wing institutions into a leftist government because of the constant wars and strong alliance with Western countries.

As for dictatorship, Israel was lucky in this department. Every one of Israel's leaders has seen himself at the whim of the people and thus not beyond reproach or recall, similar to the United States.

As for military junta, it is wholly unnecessary. Most of Israel's Prime Ministers have been superior officers in the Israeli Army and the constant wars meant that the army is well-supported and stocked. Secondly, Israel maintains the Western tradition of having military authority subservient to civil authority.