The deep enmity of Shi’ite Iran towards the US and Israel does not come from the usual political and economic reasons as many suppose, according to an article in The Jerusalem Post by Lela Gilbert entitled “Iran’s aggression and the Shia apocalypse” (https://www.jpost.com/Opinion/Irans-aggression-and-the-Shiite-apocalypse-598904). In fact it comes from the religion of Shi’ism that is deeply ingrained in the culture of the Iranian nation and which has an apocalyptic vision of the future.
Shi’ism results from the beginning of Islam, when after Mohammed died in 632 ce he had not named a successor. As a result, his immediate followers decided to elect chief among them Abu Bakr as Caliph, both as spiritual and temporal leader. These became the Sunni Muslims. However, there were many who thought his successor should be a blood relative, and his only surviving blood relative was his grandson Ali, son of his daughter Fatimah and son-in-law Hussein. His followers became the Shia
After Mohammed’s death the Sunni Muslims raised an army and began their series of conquests, including Damascus in 634, Jerusalem in 639, and North Africa in 652. The inevitable Sunni-Shia clash came at Karbala in what is now Iraq in 680 when the Shia army under Ali were defeated by a much larger Sunni army under the Caliph. From then on the Shia were a persecuted heretical minority of Islam that developed its own culture.
Although there are several sub-sects of Shia Islam, the majority and that practiced in Iran is what is known as “Twelver” Islam. They believe that after the death of Ali there were 10 other Imams, who were his descendants and for the most part were secret. But, the Twelth Imam is the Mahdi or savior (obviously derived from the Judaic concept of the Messiah that Christianity also adopted) known as the Hidden Imam. The Twelver Shia, i.e. the Iranians and their proxies, believe that at the end of days when the hidden Imam appears there will be be an apocalyptic bloody conflict between the Muslim believers (i.e the Shia) and the infidels, which of course the Shia will win.
According to the article by Lela Gilbert, Iranian foreign policy is specifically devoted to bringing about the conditions of this apocalypse that they expect to win and defeat Israel, the US and the West in a cataclysmic bloody conflict. While many in the West are looking for Iran to show rational behavior, the Iranians are in fact waiting for the Mahdi to appear. So when the crowds in Tehran shout “Death to Israel”, “Death to America,” they really mean it!