Remember this series is a series of witness encounters. Young people in my area ask me, "How do you know?" I am trying to answer.
A corollary question to that of knowledge is the question, "Who am I (who are you, who is anyone) to say what is right and wrong in matters of religion, ethics, philosophy or anything else?" These two questions have to get some kind of sentient answers if any portion of our culture is to remain even nominally Christian.
We can dismiss some commentators, regardless of the sanctimony of their offerings. Let me list a few.
We shall not and should not listen to the fellow whose life/family/business practice/et al, is a mess. We shall not and should not take marriage advice from the fellow who has been married ten or eleven times. He is an expert on divorce, not marriage. He believes in weddings, not marriage. Perhaps he should save us all and buy a bakery next door to a florist.
We shall not and should not take advice from someone with a clearly selfish agenda. If our adviser takes three offerings before he gets through his commercial to his actual advice, we see his real intentions. If we have to buy something to gain access to his site, we see his agenda. Single issue parties/individuals will betray their agenda early and often or ultimately and finally. Regardless, we should not spend too much time with them.
Agendas come at us from other angles as well, and often reveal themselves, finally, in the form of "ulterior motives." For instance, the fellow who argues we should provide forgiveness to him for his theft while his other hand reaches for our other pocket exposes his "ulterior motive." He is not asking for forgiveness but access. We ought to forgive whenever we can, like God does, and forget the transgression so much as we can, in the same way God does. We are not required to go down the same path. The Apostle Paul lists at least two persons he surrenders to Satan for the sake of their souls. He means he will not allow them to stand in the sheepfold, pretending to be sheep, perhaps even wanting to be sheep, while their fangs take a frightful toll on the actual sheep.
Cheap repentance should not result in meaningless forgiveness but, rather, with confrontational love. There are too many times our ineffectual arete (man made, and so fallible) forgiveness provides just enough emotional support to the sin sick person to help maintain them in their level of illness.
We might also say we are right to avoid even sincere advice that leads to self-destruction or to the harm of others. We should probably not have to say Timothy McVeigh erred when he detonated a truck bomb in front of a federal building in Oklahoma City. If we easily accept the question, "Who is to say what is right and what is wrong?" we have to blindly absolve Bundy, Stalin, Madoff, et al.
Let me pause to reveal my ulterior motive or, at least, one might say, my hidden argument. These are obvious exceptions to the whole range of Authority. These are Straw Men, hastily set up and then easily kicked down to dust, so that they answer the posed question but without any deep thought. I put them forward because they are simply understood and explained. Each is as easily accepted. What are they worth as arguments or even tool for argument?
Each one serves as the follow-up to the initial question. They are directive in nature. If the implied answer to the question "Who is to say…" is simply "No one, I guess…" we imply any idea is as good as any other idea. However, when we pose the follow-up questions, as if we are to ask, "Do you really take existence to be so nebulous as to be vacant of any objective right and wrong?" we introduce limits or boundaries to the equation. I scarcely need to say, the introduction of any limits or boundaries to the supposedly infinite expanse of antinomianism (lawlessness, or "instead of law") reshapes the proposed purpose.
We can then go on to say all cultures (of all tribes and tongues) develop some kind of ethics, if only by example or model, because in human cultures we invariably find someone who is both willing and able to sacrifice some personal luxury or autonomy for the greater good of the culture. When, therefore, we start to look for an answer to the vast initial question, we establish first that there are limits to what can be deemed ethical, by which we mean "acceptable because admirable."
Opinion s expressed here are mine alone.