Civil religion begins and ends with the freedom of human beings:
"There is only one force of history that can break the reign of hatred and resentment...and that is the force of human freedom..." - George Bush
That is why atheists are right and rational to call "God" into question: they understand that the underlying premise of civil religion with which they agree -- that is, absolute human freedom -- has no need of God. In fact, what they know and what the Christians engaged in civil religion don't is that this underlying premise would work better without him. (So called "New Atheism" is far more practical than it is philosophical.) Atheists are not trying to turn Christians into something different - into atheists. They are trying to turn Christians into better versions of what they already are.
True religion begins and ends with the freedom of God. This is a freedom that atheists and Christians cannot be free from, because it is a freedom for them. If there is a centre to Barth's theology, Clifford Green says it is this:
the freedom of God acting in love toward humanity in Jesus Christ, which sets us free in all spheres of life – politics, art, economics, science, and especially theology and church – for a life of co-humanity and the praise of God.