Speaking as a former hardhead, there is nothing you can do or say to him that will get him to change his mind. He will either one day have a light bulb moment or he will not. You can explain to him what science really is until you're blue and he still wouldn't budge.
My advice to you is to avoid this topic all together with him and move on. Again, he will either one day have a light bulb moment or he will not.