So don't waste your time. But what you can do is listen to them when they are trying to change your mind.
I had this born-again christian friend and she would often try changing my mind to become born-again and those of you who know me know I will never become a born-again christian. I am quite content with my beliefs. I am a quasi-Buddhist, Spinoza kinda person, more is another story altogether.
Anyway, for years she badgered me to convert telling me I was going to hell and that I was wrong and Satan and his minions would take up residence in me... yada yada... then one day she told me she became a Buddhist.
Imagine my shock. All her badgering me to change actually made her change her mind.
I never tried to make her change her mind. I just lent her the occasional book about the Dalai Lama or Buddhism when she said she was interested.
I often wondered whether she was listening to all the stuff she told me and realized it didn't make sense. Her talking about it made her reprocess her beliefs?
I am an avid believer in just listening to people. I believe there is a grain of truth in everything if we but listen.
Another person decided he was going to call me every name under the sun because he was sure climate change wasn't real. So while he was using the ad homs I patiently explained to him what concerned me about climate change. We went back and forth for several days. Then finally he changed his mind. He became quite enthusiastic with me and tweeted my praises for a number of days. I was asked if I got an apology for the ad homs. I didn't care about the ad homs, but I was elated this guy listened to me.
To be KIND is more important than to be right. Many times, what people need is NOT a brilliant mind that speaks but someone that listens.
The other thing we can do is pretend we already know what the other person is saying and never really hear them at all. One day I was listening to someone say something that I'd heard him say 100times at least and then I finally heard what he said.
Listening to what someone says is actually one of the most difficult things we can actually do. Two people describing themselves as GOP or Democrat or left or conservative can feel radically different about things despite using the same label.
So perhaps the first lesson in changing someone's mind is to ignore the labels and agree to listen to their point of view and then you will see who's mind needs changing.