God and stopping sin

 In the Bible and probably today God uses destructive forces to stop sin, rather than addressing the sin directly with each person. God could attack a person about to sin with relevant nightmares or any number of things that would highlight the sin without talking to them directly and without destroying whole countries. 

When God talks to Cain after his sin,  Cain does not appear to keep murdering people. God talks to Cain before the murder, but God could have had Cain trip and hit his own head as he reached out to murder Abel. If he kept trying, then God might finally kill Cain. Cain would have obviously failed.

Another thing is God will harden people's minds to cause certain events, but doesn't change people's thinking to stop them from sinning. 

God does supernatural things, but seems to be working to an adjenda or process we don't know. 

It will be interesting to see if God ever explains why.