heaven is an idea (a concieved place for the dead), another word for the afterlife... this term has been around before christianity... just like there are many different names for GOD or the Devil, it isn't that tuff to grasp.

See what your trying to state is that... people exsisted for 1000's for years w/o mention of GOD, then christianity came along and spelled out Jesus, GOD, & Heaven...