Because it was inevitable. What passes for the "Conservatism" now is merely autocratic Stalinism with a veneer of biblical fundamentalism slapped across it. Once Communism ceased to be called Communism, the post-Reagan "conservatives" felt safe to reveal themselves for what they really are: Fascist-influenced communists. Think that's ridiculous? Then why does leader of the alt-right Steve Bannon profess to be a Leninist?
While this analysis is accurate, I just don't understand how so many who claim to be religious simply fall in line by supporting in all likelihood the least Christian candidate for president we've ever had.