The thing is
they claim to be.
After reading the article, I think the author needs to apply Occam's Razor to the problem. The actual situation is that most of the people who claim to be Christian aren't. For most people, their church is a social club, not faith.
For example, the author is still willing to condemn those who cohabitate. Now, according to the article, fully one in five evangelicals think adultery in marriage is OK. I'm not even married, and I would never consider fooling around on my partner, and have not, despite over two years of separation while I go to school.
Who's more Christian, the person who observes the rituals but ignores the precepts, or the person who ignores the rituals but follows the precepts? Most of the evangelical movement in the US seems to be made up of the former, not the latter.
