The leftist is a collectivist and the Christian is essentially an individualist. Salvation comes to us retail whereas acceptance by the group produces the this-worldly salvation for the collectivist. So the key to group acceptance is submission to the group and conformity. The great paradox of Christianity, its mystery, is that submission to Christ, the picking up of the cross and following, results in liberation and empowerment. So in Christianity the individual is liberated and empowered which is threatening to the group which seeks to empower the collective at the expense of the individual.
The miracle of individual liberation and empowerment in Christianity is not only anathema to the leftist but it is invisible to him. He believes that he alone is the master of his fate even though he is the victim of the greatest deception and is in a tragic and mortal bondage.
I could not agree with you more when you say:
I’ve also started coming to the conclusion that political differences are not fundamentally political differences—i.e., socialism versus free markets. They are basically atheist-versus-believer differences.
