As separatists they may not be as effective as witnesses for Christ, but I think Warren's referencing them as "enemies" is way over the top. I couldn't help but notice he didn't say the same for the godless liberals (like the Bishops who confirmed Vicky Robinson) who are hell bent on destroying both our churches and our way of life. No criticism there. But those evil fundamentalists...
I don't, because I've butted heads with some of them. Imagine a guy who says I am a servant of Satan because I dared to correct the Bible. (I told him that he was misunderstanding a KJV anachronism.) I was an apostate because I left his inconsequential, marginalized sect to join to a "denomination that gathered to men's doctrines, not Jesus Christ." The man said, "Only in [his sect] is there liberty to worship in Spirit and in Truth." I was apostate for telling him that there was a whole world of Christians beside his sect that worship God fully.
I've never had a godless liberal say that kind of pablum. Don't get me wrong - the liberals are one of the most serious threats facing modern Christianity. Christ's harshest criticisms, however, were not directed at the liberals of his day, but rather the smug, arrogant, self-satisfied fundamentalists. The Pharisees were more dangerous to the soul than the Saducees.