That's one of the worst parts of conservatism among people who pride themselves in being conservative and yet don't really have an appreciation of what the term signifies--particularly some who plume themselves on their Christianity.
This is true enough.
We do well to be concerned about sin. Sin represents a compromise of God’s grace. This world is not a place completely bereft of God’s grace; to find such a place one would have to visit hell itself.
We also do well to recognize that when God imparts new, divinely based righteousness to those who turn back to Him for help once they understand there is nowhere else to go for help with their sinful failures, this righteousness pushes away sin. These are the “yes” promises of the gospel and they are more powerful than any “no” warning of the law. Jesus came, among other things, to show that this principle works to a T.
We can’t disregard the “no” warnings because they show us where we need to stop and ask the Lord for more help, which He will do without grudge. Sometimes this means we suffer chastisement, though the earlier we come to the Lord the less likely we will have to suffer greatly.
The ultimate punishment of banishment to hell is something that humans have no power to inflict. Ending the earthly life of, say, a person who murdered is not the end of the story for that person as far as the Lord is concerned. It is permitted however, as this is a picture of banishment to hell. Sometimes humanity needs the pictures in order to get the point.