hmm that is very interesting, after reading through the article I dont believe that they separated donations given to their church and given to other organizations.
https://www.hudson.org/files/publications/IndexGlobalPhilanthropy2007.pdf
Here is an interesting article that gives some more stats that show the picture is not cut and dry. For example non-religious doctors chose to work with poor more than religious ones.
There is also the problem with self reported numbers in that religious people claim to give more to charity than they do.
Also in studies that see how people react studies dont show differences.
https://secularhumanism.org/index.php?section=fi&page=generous_atheists
Further in the US
when you take religious donations out of the equation the states who are on the bottom for donations like pennsylvania and new york jump to number 4 and 2 respectively and those are very low religious states.
I stick to what I said (at least in the USA) that when you take religious donations out (which generally are required/expected to maintain membership) there is not a difference between secular and religious peoples donation.