As I understand it - I haven't read the book - he divides the world between those who believe that wealth is finate, and that enriching yourself means depriving someone else; and those who believe that wealth infinate, and that enriching yourself can actually create opportunities for others, for example through doing business with you.
But back to Gilder. He argues that Israel's staunchest critics belong to the former group - and hence hate over-achieving Israel, which they perceive as taking more than its fair share from its neighbours. Its supporters see the potential benefit in having a democratic, financially and technologically innovative state in the Middle East.
"The [Israel] test can be summarized by a few questions: What is your attitude toward people who excel you in the creation of wealth or in other accomplishments? Do you aspire to their excellence or do you seethe at it? Do you admire and celebrate exceptional achievement or do you impugn it and seek to tear it down?"
In fact, this doesn't really answer for me the question of why the Left hates Israel. If it was all about hating prosperity, they would hate Singapore even more.
Nor is it just about "canonization of victimhood", as Stephanie Guttman argues, flipping Gilder's argument.
But put those two things together and you're on to something. There is a large swathe of the West today which is simply self-hating: they hate the West's own colonial history, its success, its wealth, its supposed victimisation of others, its supposedly evil capitalist system etc etc etc.
Israel, to many of these people, has become a symbol of the sinful West, which is why anti-Americanism and anti-Israel feelings are so often so closely tied.