Whether it's a 'Christian/believer's' defense or chest-thumping point - it really doesn't matter. The statistics, as usually the case, are flawed. Man am I glad I went to college and aced my statisics class. Most of these kinds of polls are so flawed that it's a joke to ever quote them, but hey that's what the Watchtower does and that's what media does - so why not everybody else?
Even if there is a bit of truth to it. Here's the problem. If you asked me the volunteer survey when I was a Witness, I'd be able to say I did hours upon hours of volunteer work. After I stopped being a Witness, though, my volunteer work stopped. Most here, religious or otherwise, would probably agree that my "volunteer" work was of little if any real charitable benefit.
While JWs certainly consider their religious activities as actual volunteer work, so do countless of other religions. Playing in a band at a church? Then you're volunteering. Organize a church youth field trip? You're volunteering. Maybe some religious activitites are more legitimately charitable than others, but the point is that religions provide a structure in which members must support the church. And don't get me wrong, I'm not knocking church-sponored soup kitchens or church-sponsored help-the-homeless days - It's cool that they do those things. I'm sure there are even a few that truly do so without an agenda - but most churches are first and foremost about their own survival and growth, no different than the WT.
The question that the quoted poll fails to incorporate is if the volunteering by such religious persons is church-sponsored. And if it is - is it really a charitiable volunteer work? Most would probably say JWs, Mormons, and children's Jesus Camps are not truly charitiable - but as far as the poll is concerned - those activities are considered volunteering.
Those that are not religious, often don't have a structure that considers a ministry of non-belief as volunteer work. Think about it. That athiest girl with the message on the bus "God probably doesn't exist" - In all likelihood she doesn't consider that charitable work - and it sure wouldn't be tax-deductible. On the other hand, a religous group putting a message on a bus that says 'God Exists .etc. etc.' would consider that volunteering and - IT IS TAX DEDUCTIBLE.
So the stats are flawed. To be a bit more accurate, it would need to exclude any kind of volunteering that would be considered 'ministry related'.
At least that's my opinion. I'm relatively new out of the org though. I don't know - or I should say more accurately, don't care about religion. That doesn't mean I'm a believer or non-believer and I definitely can't be classified as athiest or agnostic. Truly no "ism" would come close to categorizing me. So I wouldn't have fit in the survey one way or the other. But - I do volunteer with my local 'search and rescue' and the humane society. And the funniest thing of all is that I think most non-believers are more likely to follow Jesus' words than the so called believers, that is they're more likely to not announce their charitable giving and truly 'not let their left hand know what the right is doing'. Now who is really Christian?