This was the response of the people after the Ten Commandments had been given and they had all heard the voice of God speaking from heaven. When the law was given they could not stand it.
We can evangelise and talk to people about their sin, and they are hardly aware of it. They may even deny that they have any sin. They have spent so long suppressing conscience, justifying themselves, and making excuses for sin that the conscience has become deadened and insensitive, and so they judge themselves by an entirely false standard. They assume that no one can see what really goes on in their hearts. They calculate that, because their fellow man can only look on the outward behaviour, God also can only do the same. This is why Paul describes the day of judgment as the day ‘when God shall judge the secrets of men by Jesus Christ according to my gospel’ (Romans 2:16). On that day, men and women will discover that they do have a conscience after all, and it was witness to all they did. They were unable to fully suppress it.