There are plenty of Christian critics of The Harbinger, who agree with the repentance part. They disagree with the methodology, in particular the claim that the US has some sort of special covenant relationship with God, and that Isaiah 9:10 is about the US. Here's that verse, from the public domain World English Bible:
- “The bricks have fallen,
- but we will build with cut stone.
- The sycamore fig trees have been cut down,
- but we will put cedars in their place.”
As I understand it, the book claims that this is a prophecy about the fall of the World Trade Center, on September 11, 2001.
Here are some such criticisms: http://www.thebereancall.org/content/harbinger-matter-critical-discernment
Thanks for reading.