Raise your hands if ya understand: B.C.

See, so I get how our years work now. It's 2007. Then comes 2008, 2009, 2010, all the way to 2099. But how did all them people do it before Jesus? Y'know, back in the BC days? How did they know when Jesus was going to be born so that they could start counting down to 0? And did their months count down too? I asked my minister and he just shook his head, so I guess he don't understand neither. Maybe the dinosaurs figured it out. They was mad smart.