People who do evil are a very small minority. Even within that very small minority, a portion of those who do evil do so out of fear or ignorance.
People are good. God has written his law on our hearts. Just look at how those who heard the dog's whining jumped into action to find the creature. Look how those volunteering at an animal shelter were ready to give the dog the care it needed. Look at the overwhelming sympathy and outrage on this site and others. Yes - good people need only realize how powerful they are.
People are not good - the 1st Chapter of Romans wasn't directed at "those" people - Paul was talking about every one of us.
And yes, He wrote His law on our hearts - but we don't follow His law - that's why we need a Savior.
(Do you know Him? Would you like to?)