We have been shamed out of speaking of hell and damnation as part of the consequences of sin. Its not that we need to speak of them obsessively. But we should use them in the same way Christ used them, and he certainly did use them in his teaching, where we have stopped altogether. The answer is simple: be not "ashamed of the doctrine of Christ". Even if that doctrine is unpopular. It is a doctrine calculated that "it might work upon the hearts of the children of men, altogether for my name’s glory."
We have largely put aside teaching it, to the detriment of our own ability to convince.
Enos 1:23 And there was nothing save it was exceeding harshness, preaching and prophesying of wars, and contentions, and destructions, and continually reminding them of death, and the duration of eternity, and the judgments and the power of God, and all these things—stirring them up continually to keep them in the fear of the Lord. I say there was nothing short of these things, and exceedingly great plainness of speech, would keep them from going down speedily to destruction. And after this manner do I write concerning them.
We are fooling ourselves if we do not believe that making the consequences of sin clear keeps people out of trouble they would have gotten themselves into.