I love that book thir!
I don't think that the evangelical movement or any of its sub-sects is in any greater of a position of advantage today in taking over in the USA than it was when it had a President directly involved and sympathetic to it's cause. Bush Jr was an ardent evangelical supporter and we are not under martial religious law today.
Currently evangelicals make up a larger portion of the Republican Party than I am currently comfortable with and I do wish they wouldn't push any one religion over another or seek state sponsorship.
I believe in religious freedom and that theocracy is an especially bad idea in the USA, and considering it seems to be the historical trend with other Republics that transition to Empires and eventually fall I would prefer our country avoid that paticular fate.