(If the below is not clear, don't waste time with it. I am writing from a glimpse and a feeling without notes save for Murray, and I cannot find the reference I am thinking of. However, I am disturbed with what is becoming a one-party Christian position. Granted, the opposing position is untenable.)
The coming election seems to be offering us a Church-State tension that has a 1700 year precedent. Without trying to dig out the notes and memories of the Church-State development from Gelasius to Leo XIII to the present, what looms large in my mind is the rather clear distinction of John Courtney Murray S.J. concerning epistemological classicism and historical consciousness.
This is important because it deals with the development that John Paul II and Benedict XVI attest to concerning Vatican II. John Paul II as Cardinal Wojtyla presents it as “enrichment of faith” in his catechism for Krakow. It represents a process that began with his dramatic experiences (and I believe with his devotion to Our Lady), developed in his thesis on the meaning of faith in St. John of the Cross, became philosophical method as phenomenology taken from Husserl via Scheler and hardened into spousal love as gift of self (the “I”) in “Love and Responsibility. From there it moved the entire Vatican Council from epistemological object to subject and was concretized as the 16 documents of the Vatican II.
I believe that the real conflict before us is not a conceptual conflict between two alternatives to a secular society, one that is friendly to natural and Christian morality, and one that is not. If we conceptualize it in those terms, then there is no alternative but to vote for the party that embraces Christian and human truths. What I fear in that is that absorption of the truly human and divine into the political and reduction of same into mere ideology. If that becomes the case, it can be manipulated by the political for political reasons.
I think that it is critical to understand that the connection and separation of Church and State in the United States is not established in terms of two objective orders of Church and State as societies. Rather, as John Courtney Murray points out, the relation of Church and State in this country is the result of the human person as the epistemological “I” in both objective orders. That “I” is both believer and citizen, and the former affects and grounds the latter. The initial freedom of that “I” comes from its exercise of self-determination to make the gift of self to the Revealing Christ. This is the ground of all political freedom and responsibility in the body politic because it is the grounding and development of the person as person. He becomes more and more person in the measure that he transcends himself as gift and reception of the revealing Christ. That is why the Christian is ground and best of citizens for a truly secular body politic. The goal is not an objectified Christendom but a secular political order based on a free self-determining faithful-become-citizen.
That is to say, that the problem is not a moral problem or a problem of conceptual morality. It is a problem of anthropology and personal sanctity. It is a problem of experiencing the Person of Christ and the interior dynamic and consciousness that corresponds to that experience. It is a problem of the year of faith. I fear that the majority of Christians will vote Republican because it’s an easy vote and it is strangely being handed to them on a platter. Such a platter is vulnerable and fungible in a society that is lukewarm and passively Christian.
 Jaroslaw Kupczak “John Paul “s Interpretation of the Second Vatican Council,” Communio (Spring-Summer 2012) 152-168.
 John Courtney Murray, S.J. “The Problem of Religious Freedom,” The Newman Press, Westminster, Maryland (1965), “The Two Views”… The problematic of religious freedom is abstract and simple. It is constructed by two related questions - the moral question of the rights of conscience, and the constitutional question… The Second View… The problematic of religious freedom is concrete and historical. Its construction begins with a scrutiny of the ‘signs of the times.’ Two are decisive… the growth of man’s personal consciousness; the second is the growth of man’s political consciousness” pp. 7, and 17.