Back in 2007 I read a book called American Fascists: The Christian Right and the War on America by Chris Hedges. As an atheist/agnostic yourself I think you would find it very informative and illuminating how Christian theocrats/Dominionists have been gaining influence within the Republican Party for decades going back to the mid-80’s. That’s when the shift to fascism within the Republican Party really begins and has been slowly growing ever since. Essentially, Evangelical Christians have hijacked the GOP and turned it into a party that is actively seeking to undermine democracy, because religionists (as you are no doubt aware) do not believe in democracy. (See also The Power Worshippers by Katherine Stewart or Building God’s Kingdom by Julie Ingersoll). So that’s the answer to your question: The dominance of the GOP by the Christian Right is what turned it into a fascist party. You’re sleeping with the enemy, my boy.