I then realized that the biggest problem with David Barton is not bad history or proof-texting.   The biggest problem is his version of Civil Religion, wherein the nation displaces the church, and America emerges as the new Israel with whom God has a special covenant.  Even the setting reinforced this idea: we sat on pews in a sanctuary; the American flag was prominently displayed; we recited the pledge of allegiance; and prayers were offered for the nation.

Consequently, in Barton’s scheme, politics replaces discipleship, and the nation, not the church, becomes the focus of our efforts towards righteousness.  Further, the church becomes a servant to the state, extolling America’s blessed history, proclaiming its righteous mission, and praising its glorious leaders.  And thus, by taking Christ’s place in the church, the nation becomes an idol. And that is something my evangelical convictions cannot countenance.

Dr. Miles S. Mullin, "David Barton, Civil Religion, and Patriotic Idolatry"