I have half a mind to put a "citation needed" tag after the infobox listing of religion as Methodist.  There certainly do not seem to be reliable sources labeling him an atheist, so I wouldn't go that far... but apart from being raised Methodist, there doesn't really seem to be evidence that he was that, either.  It seems he staunchly avoided talking about religion... I think this will have to remain unknown for now, barring any new revelations.