Being as the average rate of marriages that end in divorce is over 40% it's clear that these are the raw rates for the general demographics. The meaningful number here is the rate of marriages among them that terminate in divorce: atheists are just the least likely to get hitched in the first place, speaking nothing to the success of the perma-coupling they do pursue. No credit for not trying. Might be a good thing in general, but it's not really a basis for heckling the christianist "family values" routine.