Truth be told, I have yet to hear from a trustworthy rabbi about
the Jewish stand on the issue.
The problem is how they reconcile the act
with the commandment against sexual immorality, given
since Adam. If you are Christian, you have no such problem
'cos the prohibition was only given at Sinai. So a Christian answer
to your question will be ......... yes it is fair for the atheist
to say that?
I found a creative way around the problem. Looking at the
prohibitions for incest, it is possible to avoid committing the
"sin" by marrying your cousins. Or, for the case of Cain, marry
somebody who is not a descendant of Adam.
After some poking around, I found out some of the more creative
explanation given by Tradition. For instance, somebody said that
Cain and Abel each has a twin sister, meant for the other brother,
to minimize the effect of incest.
As with many things found in Tradition, read it with a pinch of
salt, for not everything found inside is authoritative, i.e.
aggadah.
This interface is kooky, sometimes it works, some times it
doesnt
Understand cousins are left out of the equation, but with
A&E, one of their children have to marry each other to produce
cousins for Cain to marry in the first place. Even if Cain and Abel
had twins, they still remain siblings. Some sources believe that
A&E werent the only people around. But my POV, is that they
were.
When GOD created A&E, he called it 'very good'. Sin entered
the picture and the effects of His curse were soon felt.
Generations of genetic degradation meant that by the time Sinai
came about, people could no longer have close marriages. Also there
were more than enough people to around anyway. Commandments were
given to distinguish Israel from the pagan nations around and to
put a complete stop.
There was some law going around before Sinai, probably laid down
by GOD thru the Jewish Tradition or some other way, such that
people could still marry within the family out of desperate
circumstances.
To the atheist, yes, GOD allowed incest but for the
abovementioned reasons. Does GOD practise double standards? Nope,
not if you understand that this was in His plans. Will it happen
again such that there won't be anybody around for one to multiply
with and he has to engage in incest? For everybody's sake, when
that time comes, that shouldnt be the foremost question on his
mind, but why is he left behind?