I often meet two types of Christians: those who are activists interested in preaching against violations of that part of God's Law typically known as "family values" and those who are the same but for "social justice". Too often one who is a proponent of one kind of activism is either lackluster in the other, or in some cases a sardonic critic of the other even being of any concern to the church. It makes for a laughable situation where one holds to two completely incompatible doctrines of sin, the two varying by how much the person is personally ticked off by the offense.
When I've seen people give justifications for their silence on whichever front is of not interest to them. They typically bring up inability of humans to save themselves, our powerlessness under the law, the futility of human effort, or even that law preaching isn't to get into meddling in specific violations-- which they call "legalism". But for the sin that upsets them, it gets elevated to a reason for denominational schisms.
In chimes Luther. In his debate with Erasmus in Bondage of the Will, Luther tears apart Erasmus' view of the law as being something we are able to follow:
[Erasmus had said,]"It would be ridiculous to say to a man standing in a place where two ways met, Thou seest two roads, go by which thou wilt, when one only was open."Ought to do, not can do. Can not do, but ought to do. Notice that Luther does not say, "cannot do and therefore you ought bloody well shut up about the whole nonsense." Perhaps it offends human reason even more that preachers be in a situation of preaching on that which cannot be done.
[Luther rebuts:] This, as I have before observed, is from the arguments of human reason, which thinks, that a man is mocked by a command impossible: whereas I say, that the man, by this means, is admonished and roused to see his own impotency. True it is, that we are in a place where two ways meet, and that one of them only is open, yea rather neither of them is open. But by the law it is shewn how impossible the one is, that is, to good, unless God freely give His Spirit; and how wide and easy the other is, if God leave us to ourselves. Therefore, it would not be said ridiculously, but with a necessary seriousness, to the man thus standing in a place where two ways meet, 'go by which thou wilt,' if he, being in reality impotent, wished to seem to himself strong, or contended that neither way was hedged up.
... The whole that the law does, according to the testimony of Paul, is to make known sin.
And this is the place, where I take occasion to enforce this my general reply: that man, by the words of the law, is admonished and taught what he ought to do, not what he can do: that is, that he is brought to know his sin, but not to believe that he has any strength in himself. Wherefore, friend Erasmus, as often as you throw in my teeth the Words of the law, so often I throw in yours that of Paul, "By the law is the knowledge of sin,"not of the power of the will. Heap together, therefore, out of the large Concordances all the imperative words into one chaos, provided that, they be not words of the promise but of the requirement of the law only, and I will immediately declare, that by them is always shewn what men ought to do, not what they can do, or do do And even common grammarians and every little school-boy in the street knows, that by verbs of the imperative mood, nothing else is signified than that which ought to be done, and that, what is done or can be done, is expressed by verbs of the indicative mood.[emphasis added]
Granted, too many activists let their chariots get stuck in the mud of mere legislative advocacy. Or they get burned out too easily, or make unreasonable demands on the world and themselves. In all these cases, a little doctrine of impotency would be a balm to the soul.
From this doctrine of man's impotence, however, I cannot see how sarcasm in the face of another's biblically principled concern is ever justified. Neither is the doctrine of man's impotence in any way an excuse for silence or indifference to preaching / activism. Woulnd't it be nice if we could to find a way to say to our non-allies, to those who picked the wrong virtue to espouse,
"Yes, I am a sinner, and I specifically have offended God by thought, word, and deed in the manner in which you say. I do feel a calling to witness and serve in other ways, which is reasonably to be expected given that there are many fruits and gifts of the Spirit."