When we have politicians trying to get "alternative" creation hypothesises into school books (see Texas and creationism), then just limiting politics to scientifically sound ideas would be a good first step.
While I agree with you in theory, in practice it's perfectly legitimate for politicians to be able to "try" something like that, even if it's an attempt to distort or deny scientific truth. Even in Texas, those efforts are controversial, and not guaranteed to succeed without opposition. But it wouldn't be just to simply forbid religious people from the opportunity to influence political debate when their point of view represents that of the majority, or at least a significant minority.