In UK atheists considred more moral than theists.

[Angrboda]

Turtles all the way down.  

At least..in the case of secular moral realism...there's going to be some acknowledgement that if you drill it down and down and down, theres an underlying arbitrarity.  The acknowledgement that, had things been different, they would be different.  

If assault were pleasurable and beneficial then assault would be, at least..within the confines of what a moral person could morally do.  Could have been that way.  Somehow..lord knows how, we could have evolved in such a way and live in such a world as to have made that a reality.  We didn't.  We don't.  It isn't....and there isn't anyone on earth or in heaven that could change that.  In that sense, I'm not sure that whatever arbitrarity in a secular morality is a meaningful arbitrarity - but the possibility is there.

I also enjoy noting that the fundamental units of both secular and theistic morality are the same.  I maintain that theists are wrong in their subject of emphasis, but not wrong in their approach.

I wouldn't necessarily disagree in any one point here, but I think as a practical matter, it would be more rational to base morals on the arbitrary facts of human nature rather than the equally arbitrary revealed morals of an inscrutable sky fairy. Even if we are made in his image, it is that image which we have to contend with, not a bunch of guesswork that revealed theology can never completely eliminate.