The University of Chicago conducted a worldwide survey on "Beliefs in God Across Time and Countries". While the report found that in most countries around the world, there was a slow decline in the belief in God, they found that true believers could be found in higher percentages in developing and Catholic countries.
In the Phillippines, polling revealed that 94% of the public had strong believers. Other nations in the top five of true believers were the Chile at 79%, Israel at 65.5%, Poland at 62% and the United States at 60%. The United States was notable as having the highest belief rate for a predominately Protestant population.
The report observed that religious belief had slowly eroded since the 1950s. Atheism and non belief was most prominent in Northern Europe and particuarly accute in what was East Germany at 13%
However, there were upticks in belief levels in the Russian Federation, Israel and Slovenia. The report found that belief levels were higher in older participants. The social scientists hypothesized that the increased levels were attributable to having some sense of their mortality rather than due to inculturation.
An obvious shortcoming of the survey is that non of the 30 nations that were polled were mostly Muslim. Of course, it would be dangerous to openly declare oneself apostate in such situations.