Is it important to you that your candidate's beliefs are compatible with the scientific ideas you embrace? I don't think I could vote for someone who believed the earth to be less than 10,000 years old. However, I will be voting for someone who appears to believe that Native Americans are primarily descended from Israelites despite DNA evidence to the contrary. Of course, besides "little" things like that, Mormons are generally pretty accepting of modern science, so I don't feel any great concern that Romney's religious beliefs would trump science in a way which would interfere with his ability to govern. Where do you draw your lines?