I do want to direct your attention tot his…
I just did a Veritas Forum where this came up. I explained that part of what it means to be human is to enter into grief. Our grief is different than animals, because we can grieve, for example, the death of MLK 50 years ago, and the segregation of St Louis, and the death of Michael Brown. We are more human for entering into these abstract types of grief.
In response, my atheist counterpart argued that everything we do is constructed (including morality). This is a classic subjectivist argument.
At the 45 minute mark in the video, the Q&A time begins. I asked him if he thought racial injustice was a subjective construct or if it was objectively wrong. What his response. He could not say that was a construct. He really believed it was objectively wrong. He did not think my grief about injustice was a mere construction, but an entry into truth.
That is the point. Moral truth is objective, even if we have difficulty agreeing upon it and defining it. We know it is derived from something outside ourselves. In our real world of brokenness we face, it is a dangerous sort of collaboration with evil things to deny they are really wrong. Everyone knows this, which is why even my subjectivist friend won’t live that way. To do so would be denying a truly self-evident reality.