Whether or not Bush made gains among rural and evangelical voters (and looking at county-by-county returns, especially in the South, it's hard to argue that he didn't do somewhat better in rural areas), it's clear that Kerry did not perform much better than Gore did. And Gore did terribly with those voters.
Most Democrats thought their 2004 nominee needed to do a little bit better in small-town America so he could win states like Missouri, Ohio and West Virginia. Earlier this year, with the economy sagging and with a disproportionate number of country boys dying in Iraq, it looked like Kerry might be able to improve on Gore's performance. But the Republicans were able to define Kerry as essentially foreign (in all meanings of the term) to the ways of Main Street.