Again, Democracy Lover has given me much food for thought, but there are some specific issues I wish to address here. First, in his comment below, he says that those Christians who are not fundamentalists have "a duty" to uphold the separation of church and state, as well as to make clear to non-Christians that fundamentalism is "an aberration". It is to these I wish to respond here.
To take the second first, I would never say that fundamentalism is "an aberration" of Christian teaching. There are elements within fundamentalist teaching that could be understood as heretical by those who hold to the notion of heresy. There are teachings within fundamentalism that seem to run counter to much of the modern spirit, although I think that is a misreading of fundamentalism. Like all the various branches of the Christian faith, it holds a piece, or perhaps even several pieces, of the truth, while much else that it professes is erroneous. This is no less true for mainline Protestantism, Roman Catholicism, the Orthodox Churches, and the Evangelical Churches. The disagreements concerning what is and is not true in Christian teaching is something between and among the various Christian churches, confessions, and denominations. We need answer no one outside for the veracity, or lack thereof, of the truth of Christian teaching, because that assumes there is some arbiter of Christian truth that exists outside of Christianity. What might that be?
As to the duty of mainline Christianity to uphold the constitutional separation of church and state, I concede that is always necessary. Yet, it is done in contless ways and countless times. All the mainline churches have legal and political divisions that are vigilant in defense of that principle. It is rarely discussed because it is much sexier for the press to cover violations. The denomination to which I belong, the United Methodist Church, has been an active participant in a multitude of legal cases, filing friend of the court briefs to ensure the continuation of the legal separation of church and state. What more need we do?
Simply because some Christians believe some things does not mean all those Christians are in error about everything. Simply because various Christian confessions and professions disagree on a multitude of issues does no mean we are beholden to anyone to disavow any of our Christian brothers and sisters because of the feelings and sensibilities of those who are disinclined to accept Christain teaching anyway. Secular society has as much to answer for in its destructive ideologies and pathological social practices as do various Christian groups. When was the last time they felt it necessary to even deign to respond?