As opposed to the moral relativism of the secular humanists. It's not "whatever I decide is proper," it is an adherence to thousands of years of Judeo-Christian principles which, to the dismay of many, is in direct conflict with the "what's right for me doesn't have to be right for you" rationale.
Well, in a free society folks pretty much have the right to believe whatever they want. They can prayer to space aliens or believe that Rob Schnieder is a towering comedic genius.