When you look at it, Raiders of the Lost Ark, is about two scientists racing for the same goal. They have their ideological differences, Jones does it for the the greater good, Belloq does it for fame.
But what is it that they're looking for? Not some religious artifact, no, they're on a race to build an atomic bomb.
Dr. Jones wants this for the prestige it will bring his museum, his country, it's a very patriotic cause. Belloq on the other hand, just wants his name attached to the find, he doesn't care for the means, the Nazis have the cash, so he works for them.
Now during WWII, America put its money into the development of the bomb, the Nazis however, were more interested in rockets.
This contrasts with the commitment the German leadership made throughout the war to the effort to build a rocket. They sunk enormous resources into this project, indeed, on the scale of what the Americans invested in the Manhattan Project.
- Mark Walker "Nazis and the Bomb"
Raiders of the Lost Ark supersedes that with a reality where Germany is pursuing nuclear weapons parallel with America, and not only that, but actually beats America to the punch and test the weapon first.
Belloq, dressed to be a king in the books of history, takes his bomb to an island, cameras are rolling, the whole world is watching. Belloq and all the Nazis on the project are wiped out by by a force they couldn't control.
What happens to Dr. Jones' project in the wake of all this?
The whole idea of nuclear warfare is shelved, put away in a warehouse never to be spoken of again.
It's an interesting thought, if the Nazis had been the first to unleash this devastating power, would America be willing to use it later?