Matthew 7:12 KJV
12 Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets.
Even most non-Christians live by this scripture, only they call it the "golden rule"-Do unto others as you would have them do unto you.
If everyone lived by this standard, the world would be a much nicer place to live. However, over the years, this has been distorted. People thing that others may want us to treat them badly because that is how they are treating us; thereby, they justify their own bad behavior. However, we need to remember, we are not responsible for someone else's behavior.
We can only be responsible for how we act and respond. We must rise above how others are acting and do what God has called us to do.