That was an ephemeral version of the Republican Party that is not coming back. Nothing is ever static and lasting.
As Heraclitus said two millennia ago, "you can't step into the same river twice".
The party of Eisenhower, Gerald Ford, even Reagan was a party of white, Anglo-Saxon mainline Protestants. Say what you will about Episcopalians, Presbyterians, Methodists, but by disposition they tended to instill a moderate and understated temperament in the faithful (e.g., the noted belligerent atheist Richard Dawkins said he has never met an Anglican vicar who wasn't just a really nice person).
But at this point in the 21st century, far rightwing evangelical fundamentalism has displaced the old High Protestant traditions, and confrontation and apocalyptic rhetoric is far more typical of the disposition of these religious communities. They also instill a kind of team ethos, where right-wingers who aren't even really Christians will do their bidding. Just look at all the fake phony rightwing Christians on this board who never actually attend service or actively participate in a religious community.