What about those that do not believe the gravity of a situation is much, but others think differently? Who is correct?
Some have better formed and informed consciences than others.
If they know it’s a sin, then they are taking their eternal life in their own hands rather than turned to God for repentance and forgiveness.
Those who recognize the authority of the Scriptures will always have reference to them in these matters. Note that the author cites the Scriptures for many of his references.
Those who recognize the authority of logic and natural law will have reference to these.
Those who, believing themselves to be gods, make up their own rules will simply do whatever they will. Satanists, for example, fall into this last category.
I had that attitude when I was in my late teens. I asked a priest about it. He said that I had a malformed conscience.
He was correct. I wanted to do something that was a sin and I tried to talk myself into it NOT being a sin. That works for about ten seconds.
Sociopaths have malformed consciences. YOU don't have a malformed conscience. You know better at all times.