Here. Money quote:
Arguably the most ridiculous claims made by Barton come from his book, America's Godly Heritage, where he states that 52 of the 55 signers to the Declaration of Independence were "orthodox" or "evangelical Christians." Are you kidding me???
Barton gets attacked quite a bit; and I've done some attacking myself. I think he's brought a lot of the attacking on himself though.
That he's not some nobody from Podunkville (even though, with his BA in math education from Oral Roberts University, he has the credentials of one), but is immensely influential in certain evangelical circles (i.e., the "homeschooled" crowd) has made it inevitable that his "research" would be put under the microscope and there would be a backlash against his claims.
The most thorough attacking is done by Chris Rodda -- a bit shrill in her rhetoric and extremely harsh in her criticisms. But with Barton et al., it's arguably "duly" harsh.