Virtue has no meaning if there is not an objective value to it, a perfect standard
against which our actions and choices are judged. This is why God is necessary to
the function of a moral universe: He provides, or more accurately is, that
standard. But harsh though such judgment must sometimes seem, it must also be
understood that the nature of God - and of everything - is mercy,
is compassion, is grace.
This is the reason why our earthly existence does not merely consist of the blind leading the blind, of amoral animalistic determinism. We have been given (and are continually given) an almost unimaginably great gift, that of awareness and, as a result, of choice.
This is why we left Eden. (I do not believe that we were cast from it.) And when we are prepared to return, it will be not as the ignorant creatures that we were, but as reflections of God Himself.