It has a number of problems, beginning with failure to define atheism / agnosticism. Do they mean anybody who doesn't believe in religion, or anyone who is not a committed theist? I think the concept of "God" is vague, and that even if something like the Abrahamic deity existed, it would be morally irrelevant (if the devil turned out to be more powerful, would you worship him instead?) --but I probably entertain beliefs that are equally woo.
The survey seems to assume that respondents will be Americans (e.g. when it asks who you voted for in the 2008 and 2012 presidential elections), and picked "wedge issues" (homosexuality and evolution) that are controversial among American Evangelicals, but not elsewhere. Evolution in particular would be a non-issue for the majority of Christians (Catholics, mainline Protestants, and I don't think the Orthodox about it care very much either, even as regressive as they are). In other parts of the world, abuse or social justice issues would be more relevant. At least they didn't ask about the End Times!
Some churches do not have a clear political affiliation, as the survey expects. They may be divided, or the local church may be different from the national denomination. Some people will have attended more than one church while growing up, which cannot be assumed to be similar. Also, respondents' motivation for leaving Christianity may be different from those keeping them away later in life.
I was amused by the line asking for suggestions about how churches might keep such people from leaving. What is this--market research? "Well, you could play a little more indie rock, cut down on the number of impossible things one has to believe, and not have so many witch-hunts."
“Men were prohibited from wearing short sleeve dress shirts because the crease in their elbow resembled a baby’s rear.”