If appeals to God get ruled out, either by disbelief in his existence or reluctance to rely upon it, says Matthew O’Brien then it isn’t possible to demonstrate that there are moral absolutes.
If you are going to make a moral argument, whether in the seminar room or in the public square, people today expect you to avoid invoking God. Atheists and theists alike share this expectation, with atheists eager to show that their moral knowledge and action are uncompromised by disbelief in God’s existence, and theists eager to establish the rational credentials of their moral convictions and protect themselves against charges of fideism. This expectation is unwarranted, however, because God’s existence is directly relevant to moral knowledge and action: If appeals to God get ruled out, either by disbelief in His existence or reluctance to rely upon it, then it isn’t possible to demonstrate that there are moral absolutes.
