Fewer people belived in god before jesus was born?

before baby J came along B.C. times were pretty well paganistic and god was low diety on the totem pole, even in jesus' time the amount of followers he had compared to other unified religious groups was really small....so why do christians in particular go on about how the world is in mortal jeopardy because so few people believe in god anymore when in fact the numbers are through the roof compared to the days when the bible was written for example