Funny thing about those who study and discuss philosophy, for anyone arguing abc, we can find another arguing xyz, in total contradiction to abc.
It doesn't surprise at all that someone like Alan Plantinga, apparently known for his Christian apologetics would take the position you state that he has taken (I confess to having never read any of his books).
And in response to this statement of yours: I most certainly can as these laws are universal and you can't provide a shred of evidence that they are "the result of trial and error"
I can only say, turn that statement around and see if it does not equally apply to your statement about moral laws being transcendant. Where's your proof?
Are you an atheist / materialist? - or just looking for logical fallacies
Human experience consistently repeated throughout history.