The Barmen Declaration was written and affirmed by the Confessing Church in Germany to stand in contrast to the State Church of German, which did allow itself to be co-opted by Hitler.
There is a difference between an official state church, as in 1930s Germany, and independent churches in the United States that support the government. I'm not saying it's not still nerve-wracking to see many churches line up and kowtow to the current administration and vice versa, but it's important to remember that we do still have many churches and denominations in this country that continue to stand up for justice and a Gospel that is not perverted to serve the state in an idolatrous manner.
For another full text of Barmen and some historical background (in the right-hand column beside the Declaration), you can also go to
http://www.ucc.org/faith/barmen.htm.