A comprehensive demographic study of more than 200 countries finds that there are 2.18 billion Christians of all ages around the world, representing nearly a third of the estimated 2010 global population of 6.9 billion. Christians are also geographically widespread – so far-flung, in fact, that no. GBD is the most comprehensive effort to date to measure epidemiological levels and trends worldwide. It is the product of a global research…