The danger is that outsiders may come to believe that "all Christians" believe their interpretation, and that you *have to* believe their interpretation to "be a Christian." More importantly, claims that "the Bible says xxx" bring disrepute on Scripture when the interpretation is wrong - after all, there is a difference between what it says and what LaHaye's interpretation of that is.
I read it and found it to be more about politics than anything else. Rather left-wing, blame America politics at that.