That's easy. I can be friends with people that disagree with me. If someone is a mature adult, it isn't difficult to do. You simply need to remind yourself that the odds are extremely high YOU aren't the smartest person on the planet, you don't have all the information available on any topic and there are always more than one way to address any issue.
If you don't have the ability to accept those things...well, you are worth having as a friend.