I'm not sure I agree with that part. There might be some superficial resemblance because they all claim to be Christians, but in behavior, a lot of the predominantly-white churches that the GOP panders to seem quite different from those of predominantly-black churches. While black churches seem to be an overall positive influence on their communities and society at large, the white churches seem to spend a lot more of their time on exclusionary, "culture wars" type things, that underlie a whole lot of the problems we're dealing with today.
If a white atheist in Canada can see that, I'm pretty sure a lot of black Christians in the US can see it as well.