Dallas Willard crushes the “wall of separation” argument when it comes to the First Amendment.
The First Amendment is about something Congress (and, as interpreted by the the Supreme Court and state governments) cannot do. It is not about what Christian should not do. We now live under the influence of a gigantic myth about a “wall of separation” between “church and state,” a phrase that appears nowhere in the Constitution. It is a metaphor that describes one theory of the First Amendment… The phrase may have some value in its suggestion of an institutional separation of church and state, but (my emphasis follows) it is positively demonic when it is interpreted to require separation between religious morality and the state.
Think of a world without the incredible work of William Wilberforce, who ended slavery in Great Britain without a war, or the work of Dietrich Bonhoeffer. Think of the United States, even in our mixed up views of racism now, without the work of Martin Luther King, Jr. What if these people had been forced to separate their Christian morality from their demands on the state?
…the crucial importance of Christlike leadership is found in the blessed lives of those citizens who provide knowledge, insight, and guidance, by God’s grace and for his purposes and ends in our world.
Quotes are taken from The Divine Conspiracy Continued, p. 194