“but you go evil and start to kill a few people for no reason as an adult”
Killing a person is no greater than any other sin. Lying, cheating, gossiping are also sins. Not forgiving some who wronged you is a sin. We can’t escape it, we are all sinners. Thank you Jesus for laying down Your life for us poor, miserable sinners.
No free rides, I think the deal is you have to either repent later again (if you are able to).
You are supposed to regret your sin, and to try and repent of your sin.
I do not think we are supposed to think we can do any sin you want free of retribution because you once accepted Christ. I think additionally you have to accept your own wrong doing and to be fighting the good fight against your sin nature.
NO FREE RIDES!