Comment 11 by Roedy:

Look at the countries going backwards: USA , Russia, Japan. These are countries that were superpowers but are now on the way down.

In terms of position in the table, I'd agree, but they're all distinct in the following ways:

US is going in the right direction, slowly so far but with definite movement in the past few years and probably with increasing momentum in the future. Good news.

Russia is going worryingly in the opposite direction -- the Orthodox Church has been the main beneficiary of the fall of communism, since the Soviet state made the stupid mistake of persecuting it and thus of handing it a free gift of moral legitimacy it had otherwise done nothing to deserve. Sadly a population who had never previously experienced democracy became accustomed to authoritarian institutions and after the fall of the communist party went looking for a replacement. This is bad news for Russia and hence for all of us, and with liberal groupings and inclinations weak in that country I don't see it improving any time soon.

Japan is anomalous: in all other countries there should be some reciprocal balance between the first and third columns, but here the third column (those sure of god's existence) is an even tinier number than the first -- in fact the smallest value for column 3 of all the countries listed. Partly this is due to Japan not being a historically Christian country, as others have noted; but partly also it displays the extreme social reluctance of the Japanese to openly state any opinion about religious belief.

And finally, er ... Go East Germany!