Okay, let me put it another way then:
Conservatives (Republicans) depend on the Christian Conservative vote. If you start to get Conservatives who discard those Christian ethics or morals or whatever you want to call them, the key constituency of the GOP evaporates. Yes?
Lets say a "political" Conservative who is an atheist should somehow get the nomination in the future. The Evangelicals and traditional Christians will never vote for him, may vote third party, and.... ...well, we know what happens then.