It is historically inacccurate and anachronistic to confuse, and virtually to equate, the thinking of the Declaration of Independence with a biblical world view, or with Reformation thinking, or with the idea of a Christian nation. In other words it is wrong to call for a return to "Christian America" on two counts: First, for theological reasons--because since the time of Christ there is no such thing as God's chosen nation; second, for historical reasons, as we have seen--because it is historically incorrect to record the founding of America and the formulation of the founding documents as being Christian in their origins. Yet this error is one of the most powerful ideas of our day; and on this confusion rest many of the calls to make war on secular humanism and to "restore" the Bible as the sole basis for American law and government.
Update: as clarification, even though I quote their book, I have absolutely no idea how any of these authors feel about Keyes. And to grasp their argument in whole, I recommend reading the book itself.