The original idea of Easter is to me antediluvian but think people try not to think about it. Abraham sacrificing a child was seen uncivilized two thousand or so years (if we try to make him historical) before Jesus! Plus, what is this "only son" business? God is supposed to be the creator of us all! And, many died for causes without knowing they were saving all of creation. The idea of rebirth and so on holds true and the original story (however the final belief in resurrection developed; see, e.g., Bart Ehrman's writings) has some interesting stuff in it.