Perhaps one needs to visit Jerusalem to fully understand why Donald  Trump’s recognition of the city as Israel’s capital is such a big deal.

I had the good fortune to be in Jerusalem a couple of weeks ago. It really is an astonishing city, home to some of the most religiously significant places to the three Abrahamic religions – Jews, Muslims and Christians alike.

For the Jews the Western Wall in Jerusalem’s Old City is the last remaining remnant of the Second Temple built over 2000 years ago, behind which is said to be buried the ‘Holy of Holies’ containing the Ark of the Covenant. It is the place towards which all Jews face while praying.

Between 1948, when Jordan took control of East Jerusalem, and 1967 when the Israeli army took control of Jerusalem after the Six-Day War, Jews were prohibited from visiting this holy place.

The ban deeply scarred many Jews. They are determined never to lose control over East Jerusalem and the Western Wall again.

Above the Western Wall is the Dome of the Rock – the third-holiest place in Islam. The rock itself is the place where Muslims believe the Prophet Mohammed ascended into heaven. No Muslim would like to see access to this area blocked.

The rock is also said to be the place where Abraham was tempted by God to sacrifice his son. Hence the rock is significant to Jews, Muslims and Christians, all of whom worship the God of Abraham and all of whom look to the story of Abraham’s temptation as a critical parable in their beliefs.

Overlooking these two holy sites is the Church of the Holy Sepulchre, where Jesus is said to have been crucified, died and ascended to heaven.

Being neither Jewish, Christian nor Islamic, I am able to enter and visit the Temple Mount, the Western Wall and the Church. I may not be religious but I do respect the deep beliefs others may hold, even if I do not hold those beliefs myself.

So, with such an important role to play in the three religions, can a resolution be found for Jerusalem and what is the big deal of Mr Trump recognising the city as Jewish?

I often teach negotiating techniques based on my many years as an international negotiator. I start classes with the very simple example of the shirt seller. Say the seller wants to sell a shirt for as much as they can, but for no less than $10. A buyer would like to buy a shirt for as little as they can, but no more than $15. In this circumstance the ‘negotiating space’ exists between $10 and $15.

However, if the seller wants to sell the shirt for no less than $15 and the buyers wants to pay more than $10, there is no negotiation space. The sooner the two sides realise this and walk away, the better.

For the Jewish State, it is a non-negotiable position of the current government that Jerusalem will be the capital of Israel and that the Old City including the Western Wall (and hence the Dome of the Rock) will be under Jewish control. For the Palestinians, it is non-negotiable that Jerusalem should be the capital of an independent Palestine, with the Palestinians having control of the Dome of the Rock (and hence the Western Wall).

There seems to be no ‘negotiating space’.

When the Oslo accords were agreed in the 1990s, both the Israelis and the Palestinians agreed to negotiate toward a ‘Two-State Solution’, where both would be recognised as legitimate countries, with the issue of Jerusalem to be determined late in the process.

Many Muslims believe Palestinian leader Yassir Arafat gave too much ground to the Israelis. Arafat has since died. Some Jews believed Israeli Prime Minister Yitzhak Rabin gave too much ground to the Palestinians, with a radical right wing Jew ultimately assassinating Rabin in part for those negotiations.

There are many other issues in dispute between the Israelis and the Palestinians, but no matter how hard other issues are to negotiate, it is the positions on Jerusalem that seem non-negotiable. So what of Mr Trump?

The United States has for years tried to act as the arbiter between the two sides. Mr Trump himself has said he wishes to negotiate a peace. However, by recognising Israel’s capital as Jerusalem the US government has strongly signalled to the world that the US will accept the Israeli claims to control many of the Abrahamic religions’ most solemn sites.

In doing so the US has signalled that either it is taking sides, or that it no longer understands both sides of the issue, or that even the US recognises that 2017 has seen US influence diminish so much that its opinion really doesn’t matter anymore. Perhaps it is all three.

Mr Trump cannot possibly understand the significance of what he has done. So much for ‘Making America Great Again’.