You know that heartbreak you get when someone is mean to your child, no matter how old they are? I imagine God feels that way when we are mean to His children, too.
You know how you treat a child of someone you know and respect? Even if they are behaving badly and need a little correction you still speak to them in a way that reflects the respect you have for their parent, right? I imagine that is the same way God expects us to treat His children, too.
And we are all His children.