It's actually case-sensitive, so here's a more accurate comparison: http://ngrams.googlelabs.com/graph?content=Christianity,Islam,Judaism,Buddhism,atheism&year_

It's actually case-sensitive, so here's a more accurate comparison: http://ngrams.googlelabs.com/graph?content=Christianity,Islam,Judaism,Buddhism,atheism&year_start=1820&year_end=2008&corpus=0&smoothing=3 http://ngrams.googlelabs.com/graph?content=Christianity,Isla...