You are not going to change someone's mind simply by giving him better, more accurate information. The response, most likely, will be to distort the information or to dismiss it by introducing non sequiturs.
People believe what they want to believe, even in face of contrary evidence. Very few like to admit when they are wrong, especially for something that has been believed for a considerable amount of time or induced by groupthink pressure.
Once you understand this dynamic, your goal in a conversation should be consistency in logic and much patience, as it often takes time and several conversations for someone to change his/her mind even a little.