Because God says that if you do something bad, if you harm someone, if you are sour, then people will return sourness to you.

因为上帝说过，假如你做坏事、伤害别人、对人不好，那么别人也会对你不好。

youdao

Whereas someone who wants to do you harm will probably do it again.

不过要是有人想伤害你的话，他或许会继续这样做。

youdao

Sometimes, you do something else to harm someone and you need to be forgiven.

有时候你可能也会做一些上其他人的事，你也需要被原谅。

youdao

If a person becomes unusually paranoid or suspicious, believes someone is out to get him or her, or says God told him or her to kill someone, these all indicate that the person may do something to harm someone else.

CNN: Insights on why people 'snap' and kill

Anyway, if someone wants to do you real harm, he can just hire a sicario an assassin.

NEWYORKER: The Kingpins