The idea is simple.
The world needs peace to survive the times to come. I would argue that you can turn this apparent difficulty to your own advantage. Its very smart to build a new capital. Somewhere else than in the disputed Jerusalem. I mean these things cost a lot money. Money that will be spent to ensure a prosperous future for the younger generation to enjoy.
I believe a ?global bank can be established to finance a project like this.
Come to think of it. Would the city need to be built with lots of tech and other innovations to make it resilient to climate change for instance. I like this idea. What if you have the best architects, engineers and planners to figure this out.