Do all peoples who have not heard of the Christian religion go to hell?

This question is directed at those (many here it seems) that believe you must believe in Christ to go to heaven. Many billions have never been given the opportunity to believe. Either by being born before Christ or being born in locations on Earth in which Christianity is not the norm. Has God decided that (except for atheists) people go to hell based on their geographical or temoral birthplace. Is this not more than a little unfair?