Hate the sin, not the sinner

Question: Why one hates a sinner? Why do not he just hate the sin, and not the sinner?
Answer: The reason is he is not able to differentiate in between sin and sinner. He thinks, they are one- and hence starts hating sin and sinner both.

Differentiating in between sin and sinner:
Fist lets see who is 'paapi'- He is a soul, who has accumulated karma because of which he is performing paap. So here we have definitely paap is happening in the soul- however it is happening because of the karma. And hence there is difference in the inherent nature of soul, and the paap which is happening inside.

And one who can appreciate above difference, would be able to just hate the sin, and not the sinner.

Gyaani looks at the sinner as a diseased person, and has compassion on him.