Convincing someone to change their mind?

We know that repeating the same thing, and insulting people don't work. Also if you set out to change someone's mind, you should believe he CAN change his mind. So you'd say "you are mistaken" not say "you are an idiot" or "you are evil". Lastly avoid rhetorical devices and pictures. Don't try to be clever, just speak directly. 

The mind one is wishing to change, must be both intelligent and rational -- it's a combination that a  lot of people just don't have these days. 

It is not possible in this case. 

Youi have to change their heart, to change their mind.   And God's the only one who really can do that.