By the time another banana skin of an evangelical pastor sent John McCain tumbling, fumbling for the right words to disown the association last week, many had abandoned all hope that another Republican presidency would mean change where it really counts for the rest of the world: Israel-Palestine.

Long before embarrassing footage was dug up of Pastor John Hagee preaching that Hitler did God's will by harrying Jews out of Europe to their promised land in Palestine, people of all religions and none were viewing his linking arms with Hagee as the surest sign that McCain would continue to favour Israel; to countenance the expansion of Israeli settlements in the West Bank and the blockade of Gaza.

Pastor of a megachurch in San Antonio and CEO of Global Evangelism Television, Pastor Hagee happens to be the US's leading Christian Zionist, a powerful proponent, via his Christians United for Israel lobbying organisation, of an ideology that is much better understood by Arabs than by Westerners because of the immediate bearing it has on the Israel-Palestine issue.

Christian Zionists are a large subset – an estimated 30 million strong in the US – of evangelical Christians whose rigidly literal-minded reading of Bible prophecy has locked them into a passionate embrace with the most hawkish sections of Israeli society, namely, the far right of Likud and the settler movement.

For Christian Zionists there can be no Palestinian state, first, because the Bible doesn't mention any such thing, and second, because God promised all that land and, as Pastor Hagee has claimed, "10 times more" to Israel. For Christian Zionists the world is hurtling towards its end at Armageddon, a little to the north of Jerusalem. Two-thirds of the world's Jews, all those who have not accepted Jesus as their saviour, will perish in a war that will pit an "Anti-Christ" and the Muslim world (especially Iran), and probably Russia too, against all true, born-again Christians and a returning Jesus Christ.

As this last imperative and Hagee's offensive take on the Holocaust amply prove, Christian Zionism should not be confused with philo-Semitism. Many Jews, especially Israelis, know this. The Israeli writer Gershom Gorenberg has put the case very well in his book, The End of Days: Christian Zionists "don't love real Jewish people. They love us as characters in their story, in their play, and that's not who we are, and we never auditioned for that part, and the play is not one that ends up good for us."

The Jewish component of what is collectively known as the US's Israel Lobby knows it too, but AIPAC, for example, has been less inclined to dwell on the theology; more interested in accepting and building on a source of moneyed, committed and unconditional support for Israel; more than happy to capitalise on a favourite Christian Zionist Bible tag, Genesis 12:3 in which God says to Abraham: "I will bless those who bless you, and those who curse you I will curse." The news that Pastor Hagee, who was a much-feted keynote speaker at their 2007 conference, believes that the Holocaust was God's plan for his Chosen People, has embarrassed but not surprised them.

In October 2006 I attended a three-day festival to honour Israel at Hagee's Cornerstone Church. It featured a choir singing in Hebrew, a dramatic re-enactment of Israel's history, hawkish speeches by neo-cons and a donation of half-a-million dollars to an illegal Israeli settlement. Its keynote speaker was one of the most powerful members of the Jewish Israel Lobby, Malcolm Hoenlein, of the Conference of Presidents of Major Jewish Organisations.

Pastor Hagee rounded off the grand occasion with a blood-curdling address to Iran's President Ahmadinejad, a reprise of his suggestion in his book of Bible prophecy interpretation, Jerusalem Countdown: A Warning to the World (2006), that the US hurry to Israel's defence by dropping a pre-emptive nuclear bomb on Iran.

"Listen up, Mr President of Iran! Don't threaten America! We're not afraid of you! We Christian Zionists are going to be your worst nightmare. If you remember, Pharaoh threatened Israel, and he ended up fish-food in the Red Sea!" His last words were for Jews: "Stop giving the land away! The land belongs to you! Keep it!"

Pastor Hagee is a far more influential figure than Barack Obama's Pastor, Jeremiah Wright. Although McCain is now giving grounds for hope with a pledge to scrap the development of the bunker buster – a nuclear weapon capable of demolishing Iran's underground nuclear facilities – his failure to firmly distance himself from a movement that resists any attempt by the US to act as a just broker in Israel-Palestine and talks up the case for war with Iran, remains a cause for concern.

The writer is the author of Allies for Armageddon: the Rise of Christian Zionism (Yale)