"God is immutable and so is His moral law. The nature of man has not changed,"  Except humanity's understanding of almost everything about humanity has changed.  You postulate static principles based on the interpretation of God's thinking by men who had no clue about the true nature of man's biological nature and who were writing thousands of years ago.  Surely you don't believe that God's immutable teachings must stay at the same level of interpretation as OT writers?  Do you hold that same expectation for any other human endeavor in any other field of study?  What if it turns out that the Las Vegas shooter had a massive temporal lobe tumor?  Would you judge him hell bound?  OT writers would most certainly have because they had no conception of the temporal lobe, much less the effect of temporal lobe tumors on human behavior.