Remember, all I am trying to establish for the moment is that we do not, as a matter of fact, derive our morals from scripture. Or, if we do, we pick and choose among the scriptures for the nice bits and reject the nasty. But then we must have some independent criterion for deciding which are the moral bits: a criterion which, wherever it comes from, cannot come from scripture itself and is presumably available to all of us whether we are religious or not.
