Briggs snarks at the recent study that's been doing the rounds (which I hadn't bothered to look at in any detail though I'd seen mentions of it). However, of the criticisms I've now seen this is possibly the worst; Briggs waxes sarcastic about the fact that it's the parents' religiosity which is measured, which completely misses the point, while not actually bringing any serious criticism to the table. The biggest weakness of the study is probably that it's interpreting dictator-game outcomes as a measure of ‘altruism’, which seems extremely open to question.
The fact that this is a Templeton-funded study is enough for me personally not to take it very seriously, but I do notice that some religious critics of the study (looking at you Yancey) are quick to point out that the lead researcher identifies as a ‘secular Jew’ while not mentioning that the funding source has a strong pro-religion bias.
As for the statistics, if we put aside the question of whether the dictator-game outcome means anything, the results do at least suggest that religion does not have a large positive effect on this outcome (regardless of whether the negative effect is real or not). But the fact that the breakdown by country is not given—only the researcher's conclusions about various correlations or lack thereof—makes it hard to know whether or not Simpson's paradox or other ecological fallacies are in play or have been properly accounted for. So on balance I don't think the study updates any of my own beliefs to any real extent.