All of these groups were motivated by ideology, rather than an existential threat. Before Israel's independence, the motivation for induction was ideological, whether the group was the Palmach, the Irgun or Lehi. This continued even during the early years of statehood. A consequence of such motivation is that the strong belief in ideology legitimizes virtually any means. An army based on ideological motivation becomes a sacred cow.
History is full of examples of armies using an ideological cloak to commit atrocities.
Another important element is that such motivation is very emotional. Such motivation might be based on love of nation, love of land, love of origins, love of an idea, or love of a spiritual leader. The role of the commander in an ideological army is not only to provide military leadership, but also to educate and transmit the ideology. An army motivated by ideology requires virtually no need for coercion or obligatory service because the source of motivation is based on values and ideology. The concept of normative motivation is generally less known.