Why to be casted to hell?

Ok there is a christian movie to help their students become christians and have faith in Jesus i think its called Letter From Hell. Well my little cousin showed me it i said no but he insisted so i agreed. In the movie the fictional character gets sent to hell because he did not acknowledge Jesus as his savior. But here is my question before Jesus was born there existed civilization so should they have went to hell because they didn't acknowledge something that didn't exist yet or did it not count what do you think. Yes i have extreme faith in the lord and god but it got me thinking.