Recently a new member here at TWEB attack biblical ethics as being subjective, subjective to God. Which makes sense, but God's law would still be objective to mankind. He suggested or inferred that moral realism was preferable because it posed that objective moral facts actually exist;

Here is a definition that I think is correct:

Moral Realism (or Moral Objectivism) is the meta-ethical view that there exist such things as moral facts and moral values, and that these are objective and independent of our perception of them or our beliefs, feelings or other attitudes towards them. Therefore, moral judgments describe moral facts, which are as certain in their own way as mathematical facts.
The questions are, where do these moral facts exist? And how are we obligated to them if they do exist?