But all the experimental evidence so far suggests that his assertion is correct. So much the better for idealism then...
>I'd suggest that Einstein's motivation for constructing
>Special and General Relativity was probably religious...
No. His motivation for constructing Special Relativity was the same as Poincare's, Minkowski's, and Lorentz's motivation for undertaking the same project: they were all trying to figure out the consequences of simultaneously believing (a) that the laws of physics look the same in all inertial reference frames, and (b) that Maxwell's equations are a good description of electromagnetic phenomena.
You can look at Abraham Pais's _Subtle Is the Lord_ and conclude that Poincare, Lorentz, or somebody else would have gotten there within the decade had Einstein not written his "On the Electrodynamics of Moving Bodies." Indeed, much of the language we use to talk about Special Relativity--"spacetime", "Lorentz transformations", "invariance of the spacetime interval"--doesn't come from Einstein, but from the others working on the same problem at the same time...
Brad DeLong