These statements by Barr have been making the rounds. Like many, I find them troubling. But as a historian, I recognize them as long-standing GOP dogma.
As this article shows, Barr has been saying stuff like this since the early 90s. au.org/blogs/wall-of-…
These have all been standard GOP talking points since the 80s. They’ve just taken on an even angrier and more apocalyptic, culture war edge in the age of Trump. 
The church and state argument has existed as long as the US has. The arguments FOR secularism have as deep and vaunted roots as Barr’s more theocratic approach.
The other “tell” for many of these conservatives is that they are frequently staunch critics of Islam and fear “Sharia Law.” They are not advocates of infusing “faith” into our public life, they favor what they perceive to be the “true” faith. That is precisely what Paine feared.
The conservative discourse around Sharia Law is just bigotry and hysteria that serves as useful GOTV messaging. blog.oup.com/2018/07/sharia…
It’s worth noting how many radical Islamophobes have been closely associated with this administration, that also claims to be so supportive of “people of faith” nytimes.com/2018/04/06/us/…
Also, Trump has long been giving shout outs to America’s Islamophobic theocrats.
