Obviously the world did NOT believe there were WMDs because the world did not support the invasion as evidenced by the pathetic, non-existant coalition.
In fact, the UN security council specifically voted against military action and Bush basically flipped his middle finger at the rest of the world.
The fact that no WMD was found is an absolute EMBARRASMENT to Bush and the U.S. We specifically distanced ourselves from the UN and world opinion by invading Iraq so it was quite a risk to begin with. If you are going to take a risk like that, you better be right!
Well, clearly it was a disastrous mistake and that is why the Republicans are paying the price.