I think this is an interesting point. I've never read a particularly compelling theistic argument for how one ascertains omnibenvolence, or from what omnibenevolence originates (certainly not omnipotence?)
I think one of the more convincing arguments for this position runs that morality requires free will and free will requires an extra-natural sphere which then in turn requires God. None of the claims in that are uncontroversial of course.
Ay, what argument is this? I'm not sure to what your antecedent ("this position") refers, but in any case, what you're saying is not ringing any bells.
I'm not making a point about why atheists can't be moral, but whether morality requires God to exist. There's a difference between belief in God and existence of God as a prerequisite. So this position is the position that God must exist for morality to exist.
I'm beginning to realize that might not have been the question though. I think it's the relevant question however. Whether atheists in fact behave morally or not seems like an empirical question rather than a philosophical one.
I can't really name a philosopher off the top of my head (I'd like to say I invented this argument myself, but that's obviously not true either
)I think Kant's position on morality covers parts of this though.
